1
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Puzzarini C, Alessandrini S. Carbamic acid and its dimer: A computational study. J Comput Chem 2024; 45:2501-2512. [PMID: 38970400 DOI: 10.1002/jcc.27442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 05/15/2024] [Accepted: 05/17/2024] [Indexed: 07/08/2024]
Abstract
A recent work by Marks et al. on the formation of carbamic acid in NH 3 -CO 2 interstellar ices pointed out its stability in the gas phase and the concomitant production of its dimer. Prompted by these results and the lack of information on these species, we have performed an accurate structural, energetic and spectroscopic investigation of carbamic acid and its dimer. For the former, the structural and spectroscopic characterization employed composite schemes based on coupled cluster (CC) calculations that account for the extrapolation to the complete basis set limit and core correlation effects. A first important outcome is the definitive confirmation of the nonplanarity of carbamic acid, then followed by an accurate estimate of its rotational and vibrational spectroscopy parameters. As far as the carbamic acid dimer is concerned, the investigation started from the identification of its most stable forms. For them, structure and vibrational properties have been evaluated using density functional theory, while a composite scheme rooted in CC theory has been employed for the energetic characterization. Our results allowed us to provide a better interpretation of the feature observed in the recent experiment mentioned above.
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Affiliation(s)
- Cristina Puzzarini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
| | - Silvia Alessandrini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
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2
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Mendolicchio M, Barone V. Accurate Vibrational and Ro-Vibrational Contributions to the Properties of Large Molecules by a New Engine Employing Curvilinear Internal Coordinates and Vibrational Perturbation Theory to Second Order. J Chem Theory Comput 2024. [PMID: 39215708 DOI: 10.1021/acs.jctc.4c00857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
The unbiased comparison between theory and experiment requires approaches more sophisticated than the basic harmonic-oscillator rigid-rotor model, for taking into account vibrational averaging effects and ro-vibrational couplings in molecules of increasing size. Second-order vibrational perturbation theory based on curvilinear internal coordinates (ICs) offers a remarkable compromise between accuracy and computational cost, thanks to the reduction of mode-mode couplings with respect to their counterparts based on Cartesian coordinates. Therefore, we have developed, implemented, and validated a general engine employing ICs, which allows the accurate evaluation of vibrational averages and ro-vibrational couplings for molecules containing up to about 50 atoms beyond the harmonic approximation. After validation of the new tool for relatively small molecules, the effectiveness of ICs has been demonstrated for some flexible and/or quite large molecular bricks of life.
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3
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Xu R, Jiang Z, Yang Q, Bloino J, Biczysko M. Harmonic and anharmonic vibrational computations for biomolecular building blocks: Benchmarking DFT and basis sets by theoretical and experimental IR spectrum of glycine conformers. J Comput Chem 2024; 45:1846-1869. [PMID: 38682874 DOI: 10.1002/jcc.27377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/01/2024] [Accepted: 04/02/2024] [Indexed: 05/01/2024]
Abstract
Advanced vibrational spectroscopic experiments have reached a level of sophistication that can only be matched by numerical simulations in order to provide an unequivocal analysis, a crucial step to understand the structure-function relationship of biomolecules. While density functional theory (DFT) has become the standard method when targeting medium-size or larger systems, the problem of its reliability and accuracy are well-known and have been abundantly documented. To establish a reliable computational protocol, especially when accuracy is critical, a tailored benchmark is usually required. This is generally done over a short list of known candidates, with the basis set often fixed a priori. In this work, we present a systematic study of the performance of DFT-based hybrid and double-hybrid functionals in the prediction of vibrational energies and infrared intensities at the harmonic level and beyond, considering anharmonic effects through vibrational perturbation theory at the second order. The study is performed for the six-lowest energy glycine conformers, utilizing available "state-of-the-art" accurate theoretical and experimental data as reference. Focusing on the most intense fundamental vibrations in the mid-infrared range of glycine conformers, the role of the basis sets is also investigated considering the balance between computational cost and accuracy. Targeting larger systems, a broad range of hybrid schemes with different computational costs is also tested.
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Affiliation(s)
- Ruiqin Xu
- Department of Physics, College of Sciences, Shanghai University, Shanghai, China
| | | | - Qin Yang
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Science, Prague, Czechia
| | - Julien Bloino
- Classe di Scienze, Scuola Normale Superiore, Pisa, Italy
| | - Malgorzata Biczysko
- Department of Physics, College of Sciences, Shanghai University, Shanghai, China
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4
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Rais N, Salta Z, Tasinato N. Theoretical investigation of the OH-initiated atmospheric degradation mechanism of CX 2CHX (X = H, F, Cl) by advanced quantum chemical and transition state theory methods. Phys Chem Chem Phys 2024; 26:19976-19991. [PMID: 38995148 DOI: 10.1039/d4cp01453g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
Halogenated olefins are anthropogenic compounds with many industrial applications but at the same time raising many environmental and health concerns. Gas-phase electrophilic addition of the OH radical to the olefinic CC bond represents the primary sink for these chemicals in the atmosphere, with the degree and type of halogenation playing a significant role in their overall reactivity. In this work, we present a theoretical investigation of the reaction mechanisms and kinetics for the reactions between the OH radical and CH2CH2 (ethylene, ETH), CF2CHF (trifluoroethylene, TFE) and CCl2CHCl (trichloroethylene, TCE), simulated by state-of-the-art protocols and methods, with the aim of providing a detailed interpretation of the available experimental results, as well as new data of relevance to tropospheric chemistry. Specifically, potential energy surfaces (PESs) are obtained using the jun-Cheap (jChS) composite scheme, whereas temperature and pressure dependent rate coefficients and product distributions in the 100-600 K temperature range are calculated within the Rice-Ramsperger-Kassel-Marcus/master equation (RRKM/ME) framework. The rates for barrierless channels are obtained from variable reaction coordinate-variational transition state theory (VRC-VTST) combined with the two transition state model. While the reactions with ETH and TFE proceed mainly via the formation of addition adducts at P = 1 atm and T = 298 K, the dominant channel for TCE is the Cl-elimination reaction. Global rate constants for the two halogenated olefins, TFE and TCE, are found to be pressure-independent, contrary to the case of ETH. The computed rate constants, as well as their temperature and pressure dependence, are in remarkable agreement with the available experimental data, and they are used to derive atmospheric lifetimes (τ) for both TFE and TCE as a function of altitude (h) in the atmosphere, by taking into account variations in the rate coefficients (k (T, P)) and [OH] concentration.
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Affiliation(s)
- Nadjib Rais
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy.
- IUSS Scuola Universitaria Superiore, Piazza della Vittoria 15, I-27100, Pavia, Italy
| | - Zoi Salta
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy.
| | - Nicola Tasinato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy.
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5
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Sharma M, Banik S, Roy TK. Performance of Effective Harmonic Oscillator Approach for the Calculations of Vibrational Transition Energies of Large Molecules. J Phys Chem A 2024; 128:5762-5776. [PMID: 38979981 DOI: 10.1021/acs.jpca.4c01583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The accuracy and performance of the effective harmonic oscillator approximation for the description of anharmonic vibrational structure calculations are tested for large molecular systems and compared with experimental values along with vibrational self-consistent field and second-order perturbation theories. The effective harmonic oscillator approach is an effective single-particle approximation where the variational parameters are the centroids and widths of the multidimensional Gaussian product functions posited as the vibrational wave functions. A comprehensive calculation for 849 transitions that include the fundamentals, two and three quanta overtone transitions, and several combination bands of three polyaromatic hydrocarbons and one DNA nucleobase with a total of 231 normal modes are assessed. A comparison of EHO results with the experimental values is done for the polyaromatic hydrocarbons, and a close agreement is found between the two results. It also offers anharmonic eigenstates and eigenfunctions that are nearly identical with vibrational self-consistent field theory. An extensive analysis on the resultant wave functions of the excited states is performed. The overall root-mean-square deviation (RMSD) between these two methods for 849 transitions understudy is only about 8.3 cm-1, suggesting the effective harmonic oscillator as a viable alternative for the reliable calculations of transition energies of large molecular systems.
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Affiliation(s)
- Mokshi Sharma
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), Jammu, Jammu and Kashmir 181143, India
| | - Subrata Banik
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur, Tamil Nadu 613401, India
| | - Tapta Kanchan Roy
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), Jammu, Jammu and Kashmir 181143, India
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6
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Glaser N, Baiardi A, Lieberherr AZ, Reiher M. Vibrational Entanglement through the Lens of Quantum Information Measures. J Phys Chem Lett 2024; 15:6958-6965. [PMID: 38940632 PMCID: PMC11247497 DOI: 10.1021/acs.jpclett.4c01298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
We introduce a quantum information analysis of vibrational wave functions to understand complex vibrational spectra of molecules with strong anharmonic couplings and vibrational resonances. For this purpose, we define one- and two-modal entropies to guide the identification of strongly coupled vibrational modes and to characterize correlations within modal basis sets. We evaluate these descriptors for multiconfigurational vibrational wave functions which we calculate with the n-mode vibrational density matrix renormalization group algorithm. Based on the quantum information measures, we present a vibrational entanglement analysis of the vibrational ground and excited states of CO2, which display strong anharmonic effects due to the symmetry-induced and accidental (near-) degeneracies. We investigate the entanglement signature of the Fermi resonance and discuss the maximally entangled state arising from the two degenerate bending modes.
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Affiliation(s)
- Nina Glaser
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Alberto Baiardi
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Annina Z Lieberherr
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Markus Reiher
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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7
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Uribe L, Lazzari F, Di Grande S, Crisci L, Mendolicchio M, Barone V. Accurate structures and rotational constants of bicyclic monoterpenes at DFT cost by means of the bond-corrected Pisa composite scheme (BPCS). J Chem Phys 2024; 161:014307. [PMID: 38958160 DOI: 10.1063/5.0216384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 06/17/2024] [Indexed: 07/04/2024] Open
Abstract
The structural, conformational, and spectroscopic properties in the gas phase of 20 bicyclic monoterpenes and monoterpenoids have been analyzed by a new accurate, reduced-cost computational strategy. In detail, the revDSD-PBEP86 double-hybrid functional in conjunction with the D3BJ empirical dispersion corrections and a suitable triple-zeta basis set provides accurate geometrical parameters, whence equilibrium rotational constants, which are further improved by proper account of core-valence correlation. Average deviations within 0.1% between computed and experimental rotational constants are reached when taking into account the vibrational corrections obtained by the B3LYP functional in conjunction with a double-zeta basis set in the framework of second-order vibrational perturbation theory. In addition to their intrinsic interest, the studied terpenes further extend the panel of systems for which the proposed strategy has provided accurate results at density functional theory cost. Therefore, a very accurate yet robust and user-friendly tool is now available for systematic investigations of the role of stereo-electronic effects on the properties of large systems of current technological and/or biological interest by experimentally oriented researchers.
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Affiliation(s)
- Lina Uribe
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
| | - Federico Lazzari
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Silvia Di Grande
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
| | - Luigi Crisci
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Marco Mendolicchio
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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8
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Di Grande S, Barone V. Toward Accurate Quantum Chemical Methods for Molecules of Increasing Dimension: The New Family of Pisa Composite Schemes. J Phys Chem A 2024; 128:4886-4900. [PMID: 38847454 DOI: 10.1021/acs.jpca.4c01673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
The new versions of the Pisa composite scheme introduced in the present paper are based on the careful selection of different quantum chemical models for energies, geometries, and vibrational frequencies, with the aim of maximizing the accuracy of the overall description while retaining a reasonable cost for all the steps. In particular, the computation of accurate electronic energies has been further improved introducing more reliable complete basis set extrapolations and estimation of core-valence correlation, together with improved basis sets for third-row atoms. Furthermore, the reduced-cost frozen natural orbital (FNO) model has been introduced and validated for large molecules. Accurate molecular structures can be obtained avoiding complete basis set extrapolation and evaluating core-valence correlation at the MP2 level. Unfortunately, analytical gradients are not available for the FNO version of the model. Therefore, for large molecules, an accurate reduced-cost alternative is offered by evaluation of valence contributions with a double-hybrid functional in conjunction with the same MP2 contribution for core-valence correlation or by means of a one-parameter approximation. The same double-hybrid functional and basis set are employed to evaluate zero-point energies and partition functions. After the validation of the new models for small systems, a panel of molecular bricks of life has been used to analyze their performances for problems of current fundamental or technological interest. The fully black-box implementation of the computational workflow paves the way toward the accurate yet not prohibitively expensive study of medium- to large-sized molecules also by experimentally oriented researchers.
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Affiliation(s)
- Silvia Di Grande
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
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9
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Puzzarini C, Ye H, Alessandrini S. Isomerism of CH 2 SO : Accurate structural, energetic, and spectroscopic characterization. J Comput Chem 2024; 45:777-786. [PMID: 38116807 DOI: 10.1002/jcc.27283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/24/2023] [Accepted: 11/28/2023] [Indexed: 12/21/2023]
Abstract
A recent work [Ye et al. Mon. Not. R. Astron. Soc. 2023, 525, 1158] on the gas-phase formation of t-HC(O)SH, already detected in the interstellar medium, pointed out that the trans form of HC(S)OH is a potential candidate for astronomical observations. Prompted by these results, theCH 2 SO family of isomers has been investigated from an energetic point of view using a double-hybrid density functional in combination with a partially augmented triple-zeta basis set. This preliminary study showed that the most stable species of the family are the cis and trans forms of HC(O)SH and HC(S)OH. For their structural and spectroscopic characterization, a composite scheme based on coupled cluster (CC) calculations that incorporates up to the quadruple excitations and accounts for the extrapolation to the complete basis set limit and core correlation effects has been employed. This approach opens to the prediction of rotational constants with an accuracy of 0.1%. A hybrid scheme, based on harmonic frequencies computed using the CC singles, doubles and a perturbative treatment of triples method (CCSD(T)) in conjunction with a quadruple-zeta basis set, allowed us to obtain fundamental vibrational frequencies with a mean absolute error of about 1%.
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Affiliation(s)
- Cristina Puzzarini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
| | - Hexu Ye
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
| | - Silvia Alessandrini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna, Italy
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10
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Fusè M, Mazzeo G, Longhi G, Abbate S, Yang Q, Bloino J. Scaling-up VPT2: A feasible route to include anharmonic correction on large molecules. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 311:123969. [PMID: 38330757 DOI: 10.1016/j.saa.2024.123969] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/18/2024] [Accepted: 01/24/2024] [Indexed: 02/10/2024]
Abstract
Vibrational analysis plays a crucial role in the investigation of molecular systems. Though methodologies like second-order vibrational perturbation theory (VPT2) have paved the way to more accurate simulations, the computational cost remains a difficult barrier to overcome when the molecular size increases. Building upon recent advances in the identification of resonances, we propose an approach making anharmonic simulations possible for large-size systems, typically unreachable by standard means. This relies on the fact that, often, only portions of the whole spectra are of actual interest. Therefore, the anharmonic corrections can be included selectively on subsets of normal modes directly related to the regions of interest. Starting from the VPT2 equations, we evaluate rigorously and systematically the impact of the truncated anharmonic treatment onto simulations. The limit and feasibility of the reduced-dimensionality approach are detailed, starting on a smaller model system. The methodology is then challenged on the IR absorption and vibrational circular dichroism spectra of an organometallic complex in three different spectral ranges.
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Affiliation(s)
- Marco Fusè
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy.
| | - Giuseppe Mazzeo
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy
| | - Giovanna Longhi
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy; Istituto Nazionale di Ottica (INO), CNR, Research Unit of Brescia, c/o CSMT, VIA Branze 45, 25123, Brescia, Italy
| | - Sergio Abbate
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy; Istituto Nazionale di Ottica (INO), CNR, Research Unit of Brescia, c/o CSMT, VIA Branze 45, 25123, Brescia, Italy
| | - Qin Yang
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo náměstí 542/2, 160 00, Prague, Czech Republic
| | - Julien Bloino
- Scuola Normale Superiore, Piazza dei Cavalieri, 56125, Pisa, Italy.
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11
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Mendolicchio M, Barone V. Unbiased Comparison between Theoretical and Experimental Molecular Structures and Properties: Toward an Accurate Reduced-Cost Evaluation of Vibrational Contributions. J Chem Theory Comput 2024; 20:2842-2857. [PMID: 38556752 DOI: 10.1021/acs.jctc.4c00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The tremendous development of hardware and software is constantly increasing the role of quantum chemical (QC) computations in the assignment and interpretation of experimental results. However, an unbiased comparison between theory and experiment requires the proper account of vibrational averaging effects. In particular, high-resolution spectra in the gas phase are now available for molecules containing up to about 50 atoms, which are too large for a brute-force approach with the available QC methods of sufficient accuracy. In the present paper, we introduce hybrid approaches, which allow the accurate evaluation of vibrational averaging effects for molecules of this size beyond the harmonic approximation, with special attention being devoted to rotational constants. After the validation of new tools for relatively small molecules, the β-estradiol hormone and a prototypical molecular motor have been considered to witness the feasibility of accurate computations for large molecules.
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12
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Uribe L, Di Grande S, Crisci L, Lazzari F, Mendolicchio M, Barone V. Accurate Structures and Rotational Constants of Steroid Hormones at DFT Cost: Androsterone, Testosterone, Estrone, β-Estradiol, and Estriol. J Phys Chem A 2024; 128:2629-2642. [PMID: 38530336 DOI: 10.1021/acs.jpca.4c00573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
A comprehensive analysis of the structural, conformational, and spectroscopic properties in the gas phase has been performed for five prototypical steroid hormones, namely, androsterone, testosterone, estrone, β-estradiol, and estriol. The revDSD-PBEP86 double-hybrid functional in conjunction with the D3BJ empirical dispersion and a suitable triple-ζ basis set provides accurate conformational energies and equilibrium molecular structures, with the latter being further improved by proper account of core-valence correlation. Average deviations within 0.1% between computed and experimental ground state rotational constants are reached when adding to those equilibrium values vibrational corrections obtained at the cost of standard harmonic frequencies thanks to the use of a new computational tool. Together with the intrinsic interest of the studied hormones, the accuracy of the results obtained at DFT cost for molecules containing about 50 atoms paves the way toward the accurate investigations of other flexible bricks of life.
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Affiliation(s)
- Lina Uribe
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
| | - Silvia Di Grande
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
| | - Luigi Crisci
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Federico Lazzari
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Marco Mendolicchio
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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13
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Otaki H, Ishiuchi SI, Fujii M, Sugita Y, Yagi K. Similarity scores of vibrational spectra reveal the atomistic structure of pentapeptides in multiple basins. Phys Chem Chem Phys 2024; 26:9906-9914. [PMID: 38477212 DOI: 10.1039/d4cp00064a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Vibrational spectroscopy combined with theoretical calculations is a powerful tool for analyzing the interaction and conformation of peptides at the atomistic level. Nonetheless, identifying the structure becomes increasingly difficult as the peptide size grows large. One example is acetyl-SIVSF-N-methylamide, a capped pentapeptide, whose atomistic structure has remained unknown since its first observation [T. Sekiguchi, M. Tamura, H. Oba, P. Çarçarbal, R. R. Lozada-Garcia, A. Zehnacker-Rentien, G. Grégoire, S. Ishiuchi and M. Fujii, Angew. Chem., Int. Ed., 2018, 57, 5626-5629]. Here, we propose a novel conformational search method, which exploits the structure-spectrum correlation using a similarity score that measures the agreement of theoretical and experimental spectra. Surprisingly, the two conformers have distinctly different energy and geometry. The second conformer is 25 kJ mol-1 higher in energy than the other, lowest-energy conformer. The result implies that there are multiple pathways in the early stage of the folding process: one to the global minimum and the other to a different basin. Once such a structure is established, the second conformer is unlikely to overcome the barrier to produce the most stable structure due to a vastly different hydrogen bond network of the backbone. Our proposed method can characterize the lowest-energy conformer and kinetically trapped, high-energy conformers of complex biomolecules.
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Affiliation(s)
- Hiroki Otaki
- Center for Bioinformatics and Molecular Medicine, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo, Nagasaki, Nagasaki 852-8521, Japan
| | - Shun-Ichi Ishiuchi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Masaaki Fujii
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuji Sugita
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
- Computational Biophysics Research Team, RIKEN Center for Computational Science, 7-1-26 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, 1-6-5 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Kiyoshi Yagi
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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14
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Lazzari F, Mendolicchio M, Barone V. Accurate Geometries of Large Molecules by Integration of the Pisa Composite Scheme and the Templating Synthon Approach. J Phys Chem A 2024; 128:1385-1395. [PMID: 38347709 DOI: 10.1021/acs.jpca.3c08382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
An effective yet reliable computational workflow is proposed, which permits the computation of accurate geometrical structures for large flexible molecules at an affordable cost thanks to the integration of machine learning tools and DFT models together with reduced scaling computations of vibrational averaging effects. After validation of the different components of the overall strategy, a panel of molecules of biological interest have been analyzed. The results confirm that very accurate geometrical parameters can be obtained at reasonable cost for molecules including up to about 50 atoms, which are the largest ones for which comparison with high-resolution rotational spectra is possible. Since the whole computational workflow can be followed employing standard electronic structure codes, accurate results for large-sized molecules can be obtained at DFT cost also by nonspecialists.
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Affiliation(s)
- Federico Lazzari
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Marco Mendolicchio
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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15
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Barone V. Quantum chemistry meets high-resolution spectroscopy for characterizing the molecular bricks of life in the gas-phase. Phys Chem Chem Phys 2024; 26:5802-5821. [PMID: 38099409 DOI: 10.1039/d3cp05169b] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Computation of accurate geometrical structures and spectroscopic properties of large flexible molecules in the gas-phase is tackled at an affordable cost using a general exploration/exploitation strategy. The most distinctive feature of the approach is the careful selection of different quantum chemical models for energies, geometries and vibrational frequencies with the aim of maximizing the accuracy of the overall description while retaining a reasonable cost for all the steps. In particular, a composite wave-function method is used for energies, whereas a double-hybrid functional (with the addition of core-valence correlation) is employed for geometries and harmonic frequencies and a cheaper hybrid functional for anharmonic contributions. A thorough benchmark based on a wide range of prototypical molecular bricks of life shows that the proposed strategy is close to the accuracy of state-of-the-art composite wave-function methods, and is applicable to much larger systems. A freely available web-utility post-processes the geometries optimized by standard electronic structure codes paving the way toward the accurate yet not prohibitively expensive study of medium- to large-sized molecules by experimentally-oriented researchers.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy.
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16
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Glaser N, Baiardi A, Reiher M. Flexible DMRG-Based Framework for Anharmonic Vibrational Calculations. J Chem Theory Comput 2023; 19:9329-9343. [PMID: 38060309 PMCID: PMC10753801 DOI: 10.1021/acs.jctc.3c00902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 12/08/2023]
Abstract
We present a novel formulation of the vibrational density matrix renormalization group (vDMRG) algorithm tailored to strongly anharmonic molecules described by general, high-dimensional model representations of potential energy surfaces. For this purpose, we extend the vDMRG framework to support vibrational Hamiltonians expressed in the so-called n-mode second-quantization formalism. The resulting n-mode vDMRG method offers full flexibility with respect to both the functional form of the PES and the choice of the single-particle basis set. We leverage this framework to apply, for the first time, vDMRG based on an anharmonic modal basis set optimized with the vibrational self-consistent field algorithm on an on-the-fly constructed PES. We also extend the n-mode vDMRG framework to include excited-state-targeting algorithms in order to efficiently calculate anharmonic transition frequencies. We demonstrate the capabilities of our novel n-mode vDMRG framework for methyloxirane, a challenging molecule with 24 coupled vibrational modes.
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Affiliation(s)
- Nina Glaser
- Department of Chemistry
and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Alberto Baiardi
- Department of Chemistry
and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Markus Reiher
- Department of Chemistry
and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
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17
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Barone V, Lazzari F. Hunting for Complex Organic Molecules in the Interstellar Medium: The Role of Accurate Low-Cost Theoretical Geometries and Rotational Constants. J Phys Chem A 2023; 127:10517-10527. [PMID: 38033327 PMCID: PMC10726368 DOI: 10.1021/acs.jpca.3c06649] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023]
Abstract
A new approach to computation at affordable cost of accurate geometrical structures and rotational constants for medium-sized molecules in the gas phase is further improved and applied to a large panel of interstellar complex organic molecules. The most distinctive feature of the new model is the effective inclusion of core-valence correlation and vibrational averaging effects in the framework of density functional theory (DFT). In particular, a double-hybrid functional in conjunction with a quadruple-ζ valence/triple-ζ polarization basis set is employed for geometry optimizations, whereas a cheaper hybrid functional in conjunction with a split-valence basis set is used for the evaluation of vibrational corrections. A thorough benchmark based on a wide range of prototypical systems shows that the new scheme approaches the accuracy of state-of-the-art wave function methods with the computational cost of the standard methods (DFT or MP2) routinely employed in the interpretation of microwave spectra. Since the whole computational workflow involves the postprocessing of the output of standard electronic structure codes by a new freely available web utility, the way is paved for the accurate yet not prohibitively expensive study of medium- to large-sized molecules also by nonspecialists.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, di Pisa, Piazza dei Cavalieri 7, Pisa 56125, Italy
| | - Federico Lazzari
- Scuola Normale Superiore, di Pisa, Piazza dei Cavalieri 7, Pisa 56125, Italy
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18
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De Vos J, Schröder B, Rauhut G. Comprehensive quantum chemical analysis of the (ro)vibrational spectrum of thiirane and its deuterated isotopologue. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 302:123083. [PMID: 37423098 DOI: 10.1016/j.saa.2023.123083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/11/2023]
Abstract
The (ro)vibrational spectra of thiirane, c-C2H4S, and its fully deuterated isotopologue, c-C2D4S, have been studied by means of vibrational configuration interaction theory, VCI, its incremental variant, iVCI, and subsequent variational rovibrational calculations, RVCI, which rely on multidimensional potential energy surfaces of coupled-cluster quality including up to four-mode coupling terms. Accurate geometrical parameters, fundamental vibrational transitions and first overtones, rovibrational spectra and rotational spectroscopic constants have been determined from these calculations and were compared with experimental results whenever available. A number of tentative misassignments in the vibrational spectra could be resolved and most results for the deuterated thiirane are high-level predictions, which may guide experiments to come. Besides this, a new implementation of infrared intensities within the iVCI framework has been tested for the transitions of the title compounds and are compared with results obtained from standard VCI calculations.
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Affiliation(s)
- John De Vos
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany; Department of Chemistry, Ghent University, Krijgslaan 281, 9000, Ghent, Belgium.
| | - Benjamin Schröder
- Institute for Physical Chemistry, University of Göttingen, Tammannstr. 6, 37077, Göttingen, Germany.
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
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19
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Melosso M, Alessandrini S, Spada L, Melli A, Wang X, Zheng Y, Duan C, Li J, Du W, Gou Q, Bizzocchi L, Dore L, Barone V, Puzzarini C. Rotational spectra and semi-experimental structures of furonitrile and its water cluster. Phys Chem Chem Phys 2023; 25:31281-31291. [PMID: 37955344 DOI: 10.1039/d3cp03984f] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
Rotational spectroscopy represents an invaluable tool for several applications: from the identification of new molecules in interstellar objects to the characterization of van der Waals complexes, but also for the determination of very accurate molecular structures and for conformational analyses. In this work, we used high-resolution rotational spectroscopic techniques in combination with high-level quantum-chemical calculations to address all these aspects for two isomers of cyanofuran, namely 2-furonitrile and 3-furonitrile. In particular, we have recorded and analyzed the rotational spectra of both of them from 6 to 320 GHz; rotational transitions belonging to several singly-substituted isotopologues have been identified as well. The rotational constants derived in this way have been used in conjunction with computed rotation-vibration interaction constants in order to derive a semi-experimental equilibrium structure for both isomers. Moreover, we observed the rotational spectra of four different intermolecular adducts formed by furonitrile and water, whose identification has been supported by a conformational analysis and a theoretical spectroscopic characterization. A semi-experimental determination of the intermolecular parameters has been achieved for all of them and the results have been compared with those obtained for the analogous system formed by benzonitrile and water.
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Affiliation(s)
- Mattia Melosso
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Silvia Alessandrini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Lorenzo Spada
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Alessio Melli
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Xiujuan Wang
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331, Chongqing, China.
| | - Yang Zheng
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331, Chongqing, China.
| | - Chunguo Duan
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331, Chongqing, China.
| | - Jiayi Li
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331, Chongqing, China.
| | - Weiping Du
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331, Chongqing, China.
| | - Qian Gou
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, 401331, Chongqing, China.
| | - Luca Bizzocchi
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Luca Dore
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
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20
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Puzzarini C, Linguerri R, Hochlaf M. Insights into the Molecular Structure and Spectroscopic Properties of HONCO: An Accurate Ab Initio Study. J Phys Chem A 2023; 127:9502-9512. [PMID: 37922399 PMCID: PMC10658623 DOI: 10.1021/acs.jpca.3c05741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/06/2023] [Accepted: 10/09/2023] [Indexed: 11/05/2023]
Abstract
In an effort to provide the first accurate structural and spectroscopic characterization of the quasi-linear chain HONCO in its electronic ground state, state-of-the-art computational approaches mainly based on coupled-cluster (CC) theory have been employed. Equilibrium geometries have been calculated by means of a composite scheme based on CC calculations that incorporates up to the quadruple excitations and accounts for the extrapolation to the complete basis set limit and core correlation effects. This approach is proven to provide molecular structures with an accuracy better than 0.001 Å and 0.05° for bond lengths and angles, respectively. Incorporation of vibrational effects permits this level of theory to predict rotational constants with an estimated accuracy of 0.1% or better. Vibrational fundamental bands have been evaluated by means of a hybrid scheme based on harmonic frequencies computed using the CC singles, doubles, and a perturbative treatment of the triples method (CCSD(T)) in conjunction with a quadruple-ζ basis set, with all electrons being correlated, and anharmonic corrections from CCSD(T) calculations using a triple-ζ basis set, within the frozen-core approximation. Such a hybrid approach allowed us to obtain fundamental frequencies with a mean absolute error of about 1%. To complete the spectroscopic characterization, vertical electronic excitation energies have been calculated for the lowest singlet and triplet states using the internally contracted multireference configuration interaction (MRCI) method. Computations show that HONCO dissociates into OH + NCO upon the absorption of UV-vis light. In conclusion, we are confident that the highly accurate spectroscopic data provided herein can be useful for guiding future experimental investigations and supporting the characterization of this molecule in atmospheric and astrophysical media, as well as in combustion.
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Affiliation(s)
- Cristina Puzzarini
- Dipartimento
di Chimica “Giacomo Ciamician″, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Roberto Linguerri
- Université
Gustave Eiffel, COSYS/IMSE, 5 Bd Descartes, 77454 Champs sur Marne, France
| | - Majdi Hochlaf
- Université
Gustave Eiffel, COSYS/IMSE, 5 Bd Descartes, 77454 Champs sur Marne, France
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21
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Crisci L, Di Grande S, Cavallotti C, Barone V. Toward an Accurate Black-Box Tool for the Kinetics of Gas-Phase Reactions Involving Barrier-less Elementary Steps. J Chem Theory Comput 2023; 19:7626-7639. [PMID: 37880932 PMCID: PMC10653117 DOI: 10.1021/acs.jctc.3c00857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/06/2023] [Accepted: 10/13/2023] [Indexed: 10/27/2023]
Abstract
An enhanced computational protocol has been devised for the accurate characterization of gas-phase barrier-less reactions in the framework of the reaction-path (RP) and variable reaction coordinate variational transition-state theory. In particular, the synergistic combination of density functional theory and Monte Carlo sampling to optimize reactive fluxes led to a reliable yet effective computational workflow. A black-box strategy has been developed for selecting the most suited density functional with reference to a high-level one-dimensional reference potential. At the same time, different descriptions of hindered rotations are automatically selected, depending on the corresponding harmonic frequencies along the RP. The performance of the new tool is investigated by means of two prototypical reactions involving different degrees of static and dynamic correlation, namely, H2S + Cl and CH3 + CH3. The remarkable agreement of the computed kinetic parameters with the available experimental data confirms the accuracy and robustness of the proposed approach. Together with their intrinsic interest, these results also pave the way toward systematic investigations of gas-phase reactions involving barrier-less elementary steps by a reliable, user-friendly tool, which can be confidently used also by nonspecialists.
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Affiliation(s)
- Luigi Crisci
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
- Department
of Chemical Sciences, University of Napoli
Federico II, Complesso Universitario di M.S. Angelo, via Cintia 21, I-80126 Napoli, Italy
| | - Silvia Di Grande
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, I-80138 Napoli, Italy
| | - Carlo Cavallotti
- Department
of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di Milano, I-20131 Milano, Italy
| | - Vincenzo Barone
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
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22
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Barone V, Crisci L, Di Grande S. Accurate Thermochemical and Kinetic Parameters at Affordable Cost by Means of the Pisa Composite Scheme (PCS). J Chem Theory Comput 2023; 19:7273-7286. [PMID: 37774410 PMCID: PMC10601482 DOI: 10.1021/acs.jctc.3c00817] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Indexed: 10/01/2023]
Abstract
A new strategy for the computation at an affordable cost of geometrical structures, thermochemical parameters, and rate constants for medium-sized molecules in the gas phase is proposed. The most distinctive features of the new model are the systematic use of cc-pVnZ-F12 basis sets, the addition of MP2 core-valence correlation in geometry optimizations by a double-hybrid functional, the separate extrapolation of MP2 and post-MP2 contributions, and the inclusion of anharmonic contributions in zero-point energies and thermodynamic functions. A thorough benchmark based on a wide range of prototypical systems shows that the new scheme outperforms the most well-known model chemistries without the need for any empirical parameter. Additional tests show that the computed zero-point energies and thermal contributions can be confidently used for obtaining accurate thermochemical and kinetic parameters. Since the whole computational workflow is translated in a black-box procedure, which can be followed with standard electronic structure codes, the way is paved for the accurate yet not prohibitively expensive study of medium- to large-sized molecules also by nonspecialists.
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Affiliation(s)
- Vincenzo Barone
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Luigi Crisci
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Silvia Di Grande
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56125 Pisa, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
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23
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Di Grande S, Kállay M, Barone V. Accurate thermochemistry at affordable cost by means of an improved version of the JunChS-F12 model chemistry. J Comput Chem 2023; 44:2149-2157. [PMID: 37432050 DOI: 10.1002/jcc.27187] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 06/23/2023] [Indexed: 07/12/2023]
Abstract
The junChS-F12 composite method has been improved by means of the latest implementation of the CCSD(F12*)(T+) ansatz and validated for the thermochemistry of molecules containing atoms of the first three rows of the periodic table. A thorough benchmark showed that this model, in conjunction with cost-effective revDSD-PBEP86-D3(BJ) reference geometries, offers an optimal compromise between accuracy and computational cost. If improved geometries are sought, the most effective option is to add MP2-F12 core-valence correlation corrections to CCSD(T)-F12b/jun-cc-pVTZ geometries without the need of performing any extrapolation to the complete basis set limit. In the same vein, CCSD(T)-F12b/jun-cc-pVTZ harmonic frequencies are remarkably accurate without any additional contribution. Pilot applications to noncovalent intermolecular interactions, conformational landscapes, and tautomeric equilibria confirm the effectiveness and reliability of the model.
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Affiliation(s)
- S Di Grande
- Classe di Scienze, Scuola Normale Superiore di Pisa, Pisa, Italy
- Scuola Superiore Meridionale, Napoli, Italy
| | - M Kállay
- Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Budapest, Hungary
- ELKH-BME Quantum Chemistry Research Group, Budapest, Hungary
- MTA-BME Lendület Quantum Chemistry Research Group, Budapest, Hungary
| | - V Barone
- Classe di Scienze, Scuola Normale Superiore di Pisa, Pisa, Italy
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24
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Ma J, Insausti A, Hazrah AS, Xu Y. Deciphering the non-covalent interactions in the furan⋯hexane complex using rotational spectroscopy and theoretical analyses. J Chem Phys 2023; 159:134302. [PMID: 37782256 DOI: 10.1063/5.0166935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 09/12/2023] [Indexed: 10/03/2023] Open
Abstract
The rotational spectrum of a binary complex formed between furan and n-hexane was investigated using a chirped pulse Fourier transform microwave spectrometer in the range of 2-6 GHz. While furan has only one conformer, n-hexane exists in multiple conformations. The conformational landscape of the binary complex was systematically explored by using a semiempirical conformational search tool, namely CREST. The CREST conformational candidates were subjected to further geometry optimization and harmonic frequency calculations at the B3LYP-D3BJ/def2-TZVP level of theory, resulting in 34 minima within an energy window of 5 kJ mol-1. The three most stable furan⋯hexane minima all contain the most stable n-hexane conformer subunit and are separated by relatively low conformational conversion barriers. Additional calculations were carried out to support the conclusive identification of the global minimum structure responsible for the set of assigned rotational transitions. These include calculations at the B3LYP-D3BJ level with the aug-cc-pVTZ and 6-311++G(d,p) basis sets and the MP2/def2-TZVP level, as well as the single point energy calculations at the CCSD(T)-F12/cc-pVDZ level. Further non-covalent interaction and principal interacting orbital analyses show that the synergy of the πfuran → σ*hexane and σhexane → π*furan interactions plays an important role in stabilizing the observed furan-hexane conformer.
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Affiliation(s)
- Jiarui Ma
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Aran Insausti
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
- Departamento de Química Física, Universidad del País Vasco (UPV/EHU), Barrio Sarriena s/n, Leioa, Spain
- Instituto Biofisika (UPV/EHU, CSIC), Barrio Sarriena s/n, Leioa, Spain
| | - Arsh S Hazrah
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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25
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Puzzarini C, Alessandrini S, Bizzocchi L, Melosso M. Hunting for interstellar molecules: rotational spectra of reactive species. Faraday Discuss 2023; 245:309-326. [PMID: 37318358 DOI: 10.1039/d3fd00052d] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Interstellar molecules are often highly reactive species, which are unstable under terrestrial conditions, such as radicals, ions and unsaturated carbon chains. Their detection in space is usually based on the astronomical observation of their rotational fingerprints. However, laboratory investigations have to face the issue of efficiently producing these molecules and preserving them during rotational spectroscopy measurements. A general approach for producing and investigating unstable/reactive species is presented by means of selected case-study molecules. The overall strategy starts from quantum-chemical calculations that aim at obtaining accurate predictions of the missing spectroscopic information required to guide spectral analysis and assignment. Rotational spectra of these species are then recorded by exploiting the approach mentioned above, and their subsequent analysis leads to accurate spectroscopic parameters. These are then used for setting up accurate line catalogs for astronomical searches.
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Affiliation(s)
- Cristina Puzzarini
- ROT&Comp Lab, Department of Chemistry "Giacomo Ciamician", University of Bologna, Via F. Selmi 2, I-40126 Bologna, Italy.
| | - Silvia Alessandrini
- ROT&Comp Lab, Department of Chemistry "Giacomo Ciamician", University of Bologna, Via F. Selmi 2, I-40126 Bologna, Italy.
| | - Luca Bizzocchi
- ROT&Comp Lab, Department of Chemistry "Giacomo Ciamician", University of Bologna, Via F. Selmi 2, I-40126 Bologna, Italy.
| | - Mattia Melosso
- ROT&Comp Lab, Department of Chemistry "Giacomo Ciamician", University of Bologna, Via F. Selmi 2, I-40126 Bologna, Italy.
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26
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Barone V, Uribe Grajales LM, Di Grande S, Lazzari F, Mendolicchio M. DFT Meets Wave-Function Methods for Accurate Structures and Rotational Constants of Histidine, Tryptophan, and Proline. J Phys Chem A 2023; 127:7534-7543. [PMID: 37665117 PMCID: PMC10510395 DOI: 10.1021/acs.jpca.3c04227] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/12/2023] [Indexed: 09/05/2023]
Abstract
A new computational strategy has been applied to the conformational and spectroscopic properties in the gas phase of amino acids with very distinctive features, ranging from different tautomeric forms (histidine) to ring puckering (proline), and heteroaromatic structures with non-equivalent rings (tryptophan). The integration of modern double-hybrid functionals and wave-function composite methods has allowed us to obtain accurate results for a large panel of conformers with reasonable computer times. The remarkable agreement between computations and microwave experiments allows an unbiased interpretation of the latter in terms of stereoelectronic effects.
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Affiliation(s)
- Vincenzo Barone
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Lina Marcela Uribe Grajales
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
| | - Silvia Di Grande
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
| | - Federico Lazzari
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Marco Mendolicchio
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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27
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Sharma D, Roy TK. Accuracy of Different Electronic Basis Set Families for Anharmonic Molecular Vibrations: A Comprehensive Benchmark Study. J Phys Chem A 2023; 127:7132-7147. [PMID: 37603414 DOI: 10.1021/acs.jpca.3c02874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
In this work, the accuracy and convergence of different electronic basis set families for the computation of anharmonic molecular vibrational spectroscopic calculations are benchmarked. A series of 39 different basis sets from different families following their hierarchy are assessed on VSCF and VSCF-PT2 algorithms with commonly used MP2 and DFT based B3LYP-D potentials for a set of molecular systems. Such an effort has been validated in a previous work ( J. Phys. Chem. A 2020, 124, 9203-9221) with split-valence basis sets for fundamentals and intensities. Here, fundamental transitions, vibrationally excited states, and intensities are compared with the experimental data to estimate the accuracy for a series of Jensen, Dunning, Calendar, Karlsruhe, and Sapporo basis set families. The convergence of basis sets are also compared with the large ANO basis set. Comprehensive statistical error analysis in terms of accuracy and precision was carried out to assess the performance of each basis set. It is observed that the improvement for the calculated harmonic and anharmonic values from the smaller basis sets to the medium (i.e., triple-ξ) is considerable. Beyond this, from medium to large basis sets, the convergence is slow and mostly posits nearly converged values. Basis sets with and without diffuse functions offer characteristically different accuracies and convergence patterns. Finally, recommendations are given on the choice of basis set chosen as black-box which can balance between accuracy and computational time, estimation of the errors, and their selections especially for large molecules.
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Affiliation(s)
- Dhiksha Sharma
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), Jammu, J&K 181143 India
| | - Tapta Kanchan Roy
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), Jammu, J&K 181143 India
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28
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Barone V. Accurate structures and spectroscopic parameters of α,α-dialkylated α-amino acids in the gas-phase: a joint venture of DFT and wave-function composite methods. Phys Chem Chem Phys 2023; 25:22768-22774. [PMID: 37591810 DOI: 10.1039/d3cp02503a] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Accurate computations of structural, conformational and spectroscopic properties in the gas phase have been performed for two α,α-dialkylated α-amino acids, namely aminoisobutyric acid and cyclopropylglycine. Thanks to the integration of modern double hybrid functionals and wave-function methods, several low-energy structures of the title molecules could be analyzed employing standard computer resources. The computed features of all the most stable conformers of the target amino acids closely match the corresponding spectroscopic parameters issued from microwave spectroscopic studies in the gas-phase. Together with their intrinsic interest, the accuracy of the results obtained with reasonable computer times paves the way for accurate investigations of other flexible bricks of life.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy.
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29
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Fischer TL, Bödecker M, Schweer SM, Dupont J, Lepère V, Zehnacker-Rentien A, Suhm MA, Schröder B, Henkes T, Andrada DM, Balabin RM, Singh HK, Bhattacharyya HP, Sarma M, Käser S, Töpfer K, Vazquez-Salazar LI, Boittier ED, Meuwly M, Mandelli G, Lanzi C, Conte R, Ceotto M, Dietrich F, Cisternas V, Gnanasekaran R, Hippler M, Jarraya M, Hochlaf M, Viswanathan N, Nevolianis T, Rath G, Kopp WA, Leonhard K, Mata RA. The first HyDRA challenge for computational vibrational spectroscopy. Phys Chem Chem Phys 2023; 25:22089-22102. [PMID: 37610422 DOI: 10.1039/d3cp01216f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Vibrational spectroscopy in supersonic jet expansions is a powerful tool to assess molecular aggregates in close to ideal conditions for the benchmarking of quantum chemical approaches. The low temperatures achieved as well as the absence of environment effects allow for a direct comparison between computed and experimental spectra. This provides potential benchmarking data which can be revisited to hone different computational techniques, and it allows for the critical analysis of procedures under the setting of a blind challenge. In the latter case, the final result is unknown to modellers, providing an unbiased testing opportunity for quantum chemical models. In this work, we present the spectroscopic and computational results for the first HyDRA blind challenge. The latter deals with the prediction of water donor stretching vibrations in monohydrates of organic molecules. This edition features a test set of 10 systems. Experimental water donor OH vibrational wavenumbers for the vacuum-isolated monohydrates of formaldehyde, tetrahydrofuran, pyridine, tetrahydrothiophene, trifluoroethanol, methyl lactate, dimethylimidazolidinone, cyclooctanone, trifluoroacetophenone and 1-phenylcyclohexane-cis-1,2-diol are provided. The results of the challenge show promising predictive properties in both purely quantum mechanical approaches as well as regression and other machine learning strategies.
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Affiliation(s)
- Taija L Fischer
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstraße 6, Göttingen, Germany.
| | - Margarethe Bödecker
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstraße 6, Göttingen, Germany.
| | - Sophie M Schweer
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstraße 6, Göttingen, Germany.
| | - Jennifer Dupont
- Institut des Sciences Moléculaires dOrsay, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Valéria Lepère
- Institut des Sciences Moléculaires dOrsay, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Anne Zehnacker-Rentien
- Institut des Sciences Moléculaires dOrsay, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Martin A Suhm
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstraße 6, Göttingen, Germany.
| | - Benjamin Schröder
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstraße 6, Göttingen, Germany.
| | - Tobias Henkes
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg City, Luxembourg
| | - Diego M Andrada
- Institute for Inorganic Chemistry, Saarland University, 66123 Saarbrücken, Germany
| | - Roman M Balabin
- Bond Street Holdings, Long Point Road, KN-1002 Henville Building 9, Charlestown, KN10 Nevis, St. Kitts and Nevis
| | - Haobam Kisan Singh
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam-781039, India
| | | | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam-781039, India
| | - Silvan Käser
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Kai Töpfer
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Luis I Vazquez-Salazar
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Eric D Boittier
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Giacomo Mandelli
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy
| | - Cecilia Lanzi
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy
| | - Riccardo Conte
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy
| | - Michele Ceotto
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi 19, 20133 Milano, Italy
| | - Fabian Dietrich
- Department of Physics Science, Universidad de La Frontera, Francisco Salazar 01145, Temuco, Chile
| | - Vicente Cisternas
- Department of Physics Science, Universidad de La Frontera, Francisco Salazar 01145, Temuco, Chile
| | - Ramachandran Gnanasekaran
- Vellore Institute of Technology, School of Advanced Sciences (SAS), ChemistryDivision, Chennai 600 027, India
| | - Michael Hippler
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK
| | - Mahmoud Jarraya
- U. Gustave Eiffel, COSYS/IMSE, 5 BD Descartes 77454, Champs-sur-Marne, France
| | - Majdi Hochlaf
- U. Gustave Eiffel, COSYS/IMSE, 5 BD Descartes 77454, Champs-sur-Marne, France
| | - Narasimhan Viswanathan
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, D-52072 Aachen, Germany
| | - Thomas Nevolianis
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, D-52072 Aachen, Germany
| | - Gabriel Rath
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, D-52072 Aachen, Germany
| | - Wassja A Kopp
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, D-52072 Aachen, Germany
| | - Kai Leonhard
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, D-52072 Aachen, Germany
| | - Ricardo A Mata
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstraße 6, Göttingen, Germany.
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30
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Barone V, Di Grande S, Lazzari F, Mendolicchio M. Accurate Structures and Spectroscopic Parameters of Guanine Tautomers in the Gas Phase by the Pisa Conventional and Explicitly Correlated Composite Schemes (PCS and PCS-F12). J Phys Chem A 2023; 127:6771-6778. [PMID: 37535450 PMCID: PMC10440789 DOI: 10.1021/acs.jpca.3c03999] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/21/2023] [Indexed: 08/05/2023]
Abstract
A general strategy for the accurate computation of structural and spectroscopic properties of biomolecule building blocks in the gas phase is proposed and validated for tautomeric equilibria. The main features of the new model are the inclusion of core-valence correlation in geometry optimizations by a double hybrid functional and the systematic use of wave-function composite methods in conjunction with cc-pVnZ-F12 basis sets with separate extrapolation of MP2 and post-MP2 contributions. The resulting Pisa composite scheme employing conventional (PCS) or explicitly correlated (PCS-F12) approaches is applied to the challenging problem of guanine tautomers in the gas phase. The results are in remarkable agreement with the experimental structures, relative stabilities, and spectroscopic signatures of different tautomers. The accuracy of the results obtained at reasonable cost by means of black-box parameter-free approaches paves the way toward systematic investigations of other molecular bricks of life also by non-specialists.
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Affiliation(s)
- Vincenzo Barone
- Scuola
Normale Superiore, Piazza dei Cavalieri 7, Pisa 56126, Italy
| | - Silvia Di Grande
- Scuola
Normale Superiore, Piazza dei Cavalieri 7, Pisa 56126, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, Napoli 80138, Italy
| | - Federico Lazzari
- Scuola
Normale Superiore, Piazza dei Cavalieri 7, Pisa 56126, Italy
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31
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Barone V. DFT Meets Wave-Function Composite Methods for Characterizing Cytosine Tautomers in the Gas Phase. J Chem Theory Comput 2023; 19:4970-4981. [PMID: 37479680 PMCID: PMC10413851 DOI: 10.1021/acs.jctc.3c00465] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 07/23/2023]
Abstract
A general strategy for the accurate computation of structural and spectroscopic properties of biomolecule building blocks in the gas phase has been further improved and validated with a special reference to tautomeric equilibria. The main improvements concern the use of the cc-pVTZ-F12 basis set in both DFT and CCSD(T)-F12 computations, the inclusion of core-valence correlation in geometry optimizations by double hybrid functionals, and the use of the cc-pVQZ-F12 basis set for complete basis set extrapolation at the MP2-F12 level. The resulting model chemistry is applied to the challenging problem of cytosine tautomers in the gas phase. The results are in remarkable agreement with experiment concerning both rotational and vibrational spectroscopic parameters and permit their unbiased interpretation in terms of structural and thermochemical features. Together with the intrinsic interest of the studied molecule, the accuracy of the results obtained at reasonable cost without any empirical parameter suggests that the proposed composite method can be profitably employed for accurate investigations of other molecular bricks of life.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore
di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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32
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Schröder B. Ab Initio Rovibrational Spectroscopy of the Acetylide Anion. Molecules 2023; 28:5700. [PMID: 37570670 PMCID: PMC10420331 DOI: 10.3390/molecules28155700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/22/2023] [Accepted: 07/22/2023] [Indexed: 08/13/2023] Open
Abstract
In this work the rovibrational spectrum of the acetylide anion HCC- is investigated using high-level electronic structure methods and variational rovibrational calculations. Using a composite approach the potential energy surface and dipole surface is constructed from explicitly correlated coupled-cluster accounting for corrections due to core-valence correlation, scalar relativistic effects and higher-order excitation effects. Previous approaches for approximating the latter are critically evaluated. Employing the composite potential, accurate spectroscopic parameters determined from variational calculations are presented. In comparison to the few available reference data the present results show excellent agreement with ground state rotational constants within 0.005% of the experimental value. Intensities determined from the variational calculations suggest the bending fundamental transition ν2 around 510 cm-1 to be the best target for detection. The rather weak CD stretching fundamental ν1 in deuterated isotopologues show a second-order resonance with the (0,20,1) state and the consequences are discussed in some detail. The spectroscopic parameters and band intensities provided for a number of vibrational bands in isotopologues of the acetylide anion should facilitate future spectroscopic investigations.
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Affiliation(s)
- Benjamin Schröder
- Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, 37077 Göttingen, Germany
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33
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Palanisamy N, Banik S. An approximation to the vibrational coupled-cluster method for CH-stretching of large molecules: application to naphthalene and anthracene. Phys Chem Chem Phys 2023; 25:20076-20092. [PMID: 37462438 DOI: 10.1039/d3cp01313h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
We propose an approximation to the vibrational coupled-cluster method (VCCM) to describe the CH-stretching region of the vibrational spectrum of large molecules. The vibrational modes of a molecule are divided into two sets: the target set and the bath set. The target set includes the CH stretches and the modes that are strongly coupled with the CH stretches and/or involve strong Fermi resonances with a CH stretch fundamental. The rest of the modes are in the bath set. First, the effective harmonic oscillator (EHO) approximation is invoked for the whole system to obtain the zeroth-order frequencies and modified potentials. The effects of interaction between the bath set and the target sets are included in the modified potential from the EHO calculation. The VCCM equations are constructed with the modified potential from the EHO calculations and for the target set only. The transition energies and intensities are calculated using such a truncated VCCM approximation. The proposed method is applied to calculate the IR spectra of naphthalene and anthracene. The results with three different criteria for selecting the modes in the target set are compared with the experimental IR spectra.
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Affiliation(s)
- Nivedhitha Palanisamy
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur, Tamil Nadu, India.
| | - Subrata Banik
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur, Tamil Nadu, India.
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34
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Melosso M, Jiang N, Gauss J, Puzzarini C. Hyperfine-resolved spectra of HDS together with a global ro-vibrational analysis. J Chem Phys 2023; 158:2888208. [PMID: 37139997 DOI: 10.1063/5.0148810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/17/2023] [Indexed: 05/05/2023] Open
Abstract
Despite their chemical simplicity, the spectroscopic investigation of light hydrides, such as hydrogen sulfide, is challenging due to strong hyperfine interactions and/or anomalous centrifugal-distortion effects. Several hydrides have already been detected in the interstellar medium, and the list includes H2S and some of its isotopologues. Astronomical observation of isotopic species and, in particular, those bearing deuterium is important to gain insights into the evolutionary stage of astronomical objects and to shed light on interstellar chemistry. These observations require a very accurate knowledge of the rotational spectrum, which is so far limited for mono-deuterated hydrogen sulfide, HDS. To fill this gap, high-level quantum-chemical calculations and sub-Doppler measurements have been combined for the investigation of the hyperfine structure of the rotational spectrum in the millimeter- and submillimeter-wave region. In addition to the determination of accurate hyperfine parameters, these new measurements together with the available literature data allowed us to extend the centrifugal analysis using a Watson-type Hamiltonian and a Hamiltonian-independent approach based on the Measured Active Ro-Vibrational Energy Levels (MARVEL) procedure. The present study thus permits to model the rotational spectrum of HDS from the microwave to far-infrared region with great accuracy, thereby accounting for the effect of the electric and magnetic interactions due to the deuterium and hydrogen nuclei.
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Affiliation(s)
- Mattia Melosso
- Dipartimento di Chimica "Giacomo Ciamician," Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy
| | - Ningjing Jiang
- Dipartimento di Chimica "Giacomo Ciamician," Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy
| | - Jürgen Gauss
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician," Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy
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35
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Abstract
pbqff is an open-source program for fully automating the production of quartic force fields (QFFs) and their corresponding anharmonic spectroscopic data. Rather than being a monolithic piece of code, it consists of several key modules including a generic interface to quantum chemistry codes and, notably, queuing systems; a molecular point group symmetry library; an internal-to-Cartesian coordinate conversion module; a module for the ordinary least-squares fitting of potential energy surfaces; and an improved second-order rotational and vibrational perturbation theory package for asymmetric and symmetric tops that handles type-1 and -2 Fermi resonances, Fermi resonance polyads, and Coriolis resonances. All of these pieces are written in Rust, a modern, safe, and performant programming language that has much to offer for scientific programming. This work introduces pbqff and its surrounding ecosystem, in addition to reporting new anharmonic vibrational data for c-(C)C3H2 and describing how the components of pbqff can be leveraged in other projects.
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Affiliation(s)
- Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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36
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Barone V, Fusè M. Accurate Structures and Spectroscopic Parameters of Phenylalanine and Tyrosine in the Gas Phase: A Joint Venture of DFT and Composite Wave-Function Methods. J Phys Chem A 2023; 127:3648-3657. [PMID: 37052318 PMCID: PMC10150396 DOI: 10.1021/acs.jpca.3c01174] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
A general strategy for the accurate computation of conformational and spectroscopic properties of flexible molecules in the gas phase is applied to two representative proteinogenic amino acids with aromatic side chains, namely, phenylalanine and tyrosine. The main features of all the most stable conformers predicted by this computational strategy closely match those of the species detected in microwave and infrared experiments. Together with their intrinsic interest, the accuracy of the results obtained with reasonable computer times paves the route for accurate investigations of other flexible bricks of life.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Marco Fusè
- DMMT-sede Europa, Università di Brescia, Viale Europa 11, 25121 Brescia, Italy
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37
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Alessandrini S, Melosso M, Rivilla VM, Bizzocchi L, Puzzarini C. Computational Protocol for the Identification of Candidates for Radioastronomical Detection and Its Application to the C3H3NO Family of Isomers. Molecules 2023; 28:molecules28073226. [PMID: 37049990 PMCID: PMC10096335 DOI: 10.3390/molecules28073226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/08/2023] Open
Abstract
The C3H3NO family of isomers is relevant in astrochemistry, even though its members are still elusive in the interstellar medium. To identify the best candidate for astronomical detection within this family, we developed a new computational protocol based on the minimum-energy principle. This approach aims to identify the most stable isomer of the family and consists of three steps. The first step is an extensive investigation that characterizes the vast number of compounds having the C3H3NO chemical formula, employing density functional theory for this purpose. The second step is an energy refinement, which is used to select isomers and relies on coupled cluster theory. The last step is a structural improvement with a final energy refinement that provides improved energies and a large set of accurate spectroscopic parameters for all isomers lying within 30 kJ mol−1 above the most stable one. According to this protocol, vinylisocyanate is the most stable isomer, followed by oxazole, which is about 5 kJ mol−1 higher in energy. The other stable species are pyruvonitrile, cyanoacetaldehyde, and cyanovinylalcohol. For all of these species, new computed rotational and vibrational spectroscopic data are reported, which complement those already available in the literature or fill current gaps.
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Affiliation(s)
- Silvia Alessandrini
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
| | - Mattia Melosso
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
| | - Víctor M. Rivilla
- Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir km. 4, Torrejón de Ardoz, 28850 Madrid, Spain
| | - Luca Bizzocchi
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
| | - Cristina Puzzarini
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
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38
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Perlin AL, Wolff W, Oliveira RR. Low Energy Isomers and Infrared Spectra Simulations of C 4H 3N, C 4H 4N, and C 4H 5N and Related Ions. J Phys Chem A 2023; 127:2481-2488. [PMID: 36913600 DOI: 10.1021/acs.jpca.2c09098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
The relative stability of pyrrole derivatives were investigated by applying a global minimum (GM) search for the low-lying energy structures of C4HnN (n = 3-5) clusters at neutral, anionic, and cationic states. Several low-energy structures, previously not reported, were identified. The present results reveal a preference for cyclic and conjugated systems for the C4H5N and C4H4N compounds. In particular, the structures of the cationic and neutral C4H3N species are different from the anionic ones. For the neutrals and cations, cumulenic carbon chains were found, while for the anions, conjugated open chains were obtained. Of particular relevance, the GM candidates C4H4N+ and C4H4N are different from those reported previously. For the most stable structures, infrared spectra were simulated and the main vibrational bands were assigned. Also, a comparison with available laboratory data was done aiming to corroborate with experimental detection.
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Affiliation(s)
- Amir L Perlin
- Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
| | - Wania Wolff
- Physics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
| | - Ricardo R Oliveira
- Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
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39
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Aðalsteinsson HM, Bjornsson R. Ionization energies of metallocenes: a coupled cluster study of cobaltocene. Phys Chem Chem Phys 2023; 25:4570-4587. [PMID: 36723003 DOI: 10.1039/d2cp04715b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Open-shell transition metal chemistry presents challenges to contemporary electronic structure methods, based on either density functional or wavefunction theory. While CCSD(T) is the well-trusted gold standard for maingroup thermochemistry, the accuracy and robustness of the method is less clear for open-shell transition metal chemistry, requiring benchmarking of CCSD(T)-based protocols against either higher-level theory or experiment. Ionization energies (IEs) of metallocenes provide an interesting test case with metallocenes being common redox reagents as well as playing roles as redox mediators and cocatalysts in redox catalysis. Using highly accurate ZEKE-MATI experimental measurements of gas phase adiabatic (5.3275 ± 0.0006 eV) and vertical (5.4424 ± 0.0006 eV) ionization energies of cobaltocene, we systematically assessed the accuracy of the local coupled-cluster method DLPNO-CCSD(T) with respect to geometry, reference determinant, basis set size and extrapolation schemes, PNO cut-off and extrapolation, local triples approximation, relativistic effects and core-valence correlation. We show that PNO errors are controllable via the recently introduced PNO extrapolation schemes and that the expensive iterative triples (T1) contribution can be made more manageable by calculating it as a smaller-basis/smaller PNO-cutoff correction. The reference determinant turns out to be a critical aspect in these calculations with the HF determinant resulting in large DLPNO-CCSD(T) errors, likely due to the qualitatively flawed molecular orbital spectrum. The BP86 functional on the other hand was found to provide reference orbitals giving small DLPNO-CCSD(T) errors, likely due to more realistic orbitals as suggested by the more consistent MO spectrum compared to HF. A protocol including complete basis set extrapolations with correlation-consistent basis sets, complete PNO space extrapolations, iterative triples- and core-valence correlation corrections was found to give errors of -0.07 eV and -0.03 eV for adiabatic- and vertical-IE of cobaltocene, respectively, giving close to chemical accuracy for both properties. A computationally efficient DLPNO-CCSD(T) protocol was devised and tested against adiabatic ionization energies of 6 different metallocenes (V, Cr, Mn, Fe, Co, Ni). For the other metallocenes, the iterative triples (T1) and PNO extrapolation contributions turn out to be even more important. The results give errors close to the experimental uncertainty, similar to recent auxiliary-field quantum Monte Carlo results. The quality of the reference determinant orbitals is identified as the main source of uncertainty in CCSD(T) calculations of metallocenes.
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Affiliation(s)
| | - Ragnar Bjornsson
- Science Institute, University of Iceland, 107 Reykjavik, Iceland.,Univ Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, 17 Rue des Martyrs, F-38054 Grenoble Cedex, France.
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40
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Jiang N, Melosso M, Alessandrini S, Bizzocchi L, Martin-Drumel MA, Pirali O, Puzzarini C. Insights into the molecular structure and infrared spectrum of the prebiotic species aminoacetonitrile. Phys Chem Chem Phys 2023; 25:4754-4763. [PMID: 36691972 DOI: 10.1039/d2cp05179f] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Aminoacetonitrile is an interstellar molecule with a prominent prebiotic role, already detected in the chemically-rich molecular cloud Sagittarius B2(N) and postulated to be present in the atmosphere of the largest Saturn's moon, Titan. To further support its observation in such remote environments and laboratory experiments aimed at improving our understanding of interstellar chemistry, we report a thorough spectroscopic and structural characterization of aminoacetonitrile. Equilibrium geometry, fundamental bands as well as spectroscopic and molecular parameters have been accurately computed by exploiting a composite scheme rooted in the coupled-cluster theory that accounts for the extrapolation to the complete basis set limit and core-correlation effects. In addition, a semi-experimental approach that combines ground-state rotational constants for different isotopic species and calculated vibrational corrections has been employed for the structure determination. From the experimental side, we report the analysis of the three strongest fundamental bands of aminoacetonitrile observed between 500 and 1000 cm-1 in high-resolution infrared spectra. More generally, all computed band positions are in excellent agreement with the present and previous experiments. The only exception is the ν15 band, for which we provide a revision of the experimental assignment, now in good agreement with theory.
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Affiliation(s)
- Ningjing Jiang
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Mattia Melosso
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Naples, Italy.
| | - Silvia Alessandrini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy. .,Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Luca Bizzocchi
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | | | - Olivier Pirali
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France.,SOLEIL Synchrotron, AILES beamline, l'Orme des Merisiers, 91190 Saint-Aubin, Gif-sur-Yvette, France
| | - Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
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41
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Barone V, Fusè M, Lazzari F, Mancini G. Benchmark Structures and Conformational Landscapes of Amino Acids in the Gas Phase: A Joint Venture of Machine Learning, Quantum Chemistry, and Rotational Spectroscopy. J Chem Theory Comput 2023; 19:1243-1260. [PMID: 36731119 PMCID: PMC9979611 DOI: 10.1021/acs.jctc.2c01143] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The accurate characterization of prototypical bricks of life can strongly benefit from the integration of high resolution spectroscopy and quantum mechanical computations. We have selected a number of representative amino acids (glycine, alanine, serine, cysteine, threonine, aspartic acid and asparagine) to validate a new computational setup rooted in quantum-chemical computations of increasing accuracy guided by machine learning tools. Together with low-lying energy minima, the barriers ruling their interconversion are evaluated in order to unravel possible fast relaxation paths. Vibrational and thermal effects are also included in order to estimate relative free energies at the temperature of interest in the experiment. The spectroscopic parameters of all the most stable conformers predicted by this computational strategy, which do not have low-energy relaxation paths available, closely match those of the species detected in microwave experiments. Together with their intrinsic interest, these accurate results represent ideal benchmarks for more approximate methods.
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Affiliation(s)
- Vincenzo Barone
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy,
| | - Marco Fusè
- DMMT-sede
Europa, Universitá di Brescia, viale Europa 11, 25121 Brescia, Italy
| | - Federico Lazzari
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Giordano Mancini
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
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42
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Puzzarini C, Stanton JF. Connections between the accuracy of rotational constants and equilibrium molecular structures. Phys Chem Chem Phys 2023; 25:1421-1429. [PMID: 36562443 DOI: 10.1039/d2cp04706c] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Rotational spectroscopy is the technique of choice for investigating molecular structures in the gas phase. Indeed, rotational constants are strongly connected to the geometry of the molecular system under consideration. Therefore, they are powerful tools for assessing the accuracy that quantum chemical approaches can reach in structural determinations. In this review article, it is shown how it is possible to measure the accuracy of a computed equilibrium geometry based on the comparison of rotational constants. But, it is also addressed what accuracy is required by computations for providing molecular structures and thus rotational constants that are useful to experiment. Quantum chemical methodologies for obtaining the "0.1% accuracy" for rotational constants are reviewed for systems ranging in size from small molecules to small polycyclic aromatic hydrocarbons. This accuracy for systems containing two dozen or so atoms opens the way towards future applications such as the accurate characterization of non-covalent interactions, which play a key role in several biological and technological processes.
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Affiliation(s)
- Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, via F. Selmi 2, 40126, Bologna, Italy.
| | - John F Stanton
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA.
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43
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Barone V, Di Grande S, Puzzarini C. Toward Accurate yet Effective Computations of Rotational Spectroscopy Parameters for Biomolecule Building Blocks. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020913. [PMID: 36677970 PMCID: PMC9863398 DOI: 10.3390/molecules28020913] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 01/01/2023] [Accepted: 01/12/2023] [Indexed: 01/19/2023]
Abstract
The interplay of high-resolution rotational spectroscopy and quantum-chemical computations plays an invaluable role in the investigation of biomolecule building blocks in the gas phase. However, quantum-chemical methods suffer from unfavorable scaling with the dimension of the system under consideration. While a complete characterization of flexible systems requires an elaborate multi-step strategy, in this work, we demonstrate that the accuracy obtained by quantum-chemical composite approaches in the prediction of rotational spectroscopy parameters can be approached by a model based on density functional theory. Glycine and serine are employed to demonstrate that, despite its limited cost, such a model is able to predict rotational constants with an accuracy of 0.3% or better, thus paving the way toward the accurate characterization of larger flexible building blocks of biomolecules.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-50126 Pisa, Italy
- Correspondence: (V.B.); (C.P.)
| | - Silvia Di Grande
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-50126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, I-80138 Napoli, Italy
| | - Cristina Puzzarini
- Rotational and Computational Spectroscopy Lab, Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
- Correspondence: (V.B.); (C.P.)
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44
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Tschöpe M, Rauhut G. Convergence of series expansions in rovibrational configuration interaction (RVCI) calculations. J Chem Phys 2022; 157:234105. [PMID: 36550038 DOI: 10.1063/5.0129828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Rotational and rovibrational spectra are a key in astrophysical studies, atmospheric science, pollution monitoring, and other fields of active research. The ab initio calculation of such spectra is fairly sensitive with respect to a multitude of parameters and all of them must be carefully monitored in order to yield reliable results. Besides the most obvious ones, i.e., the quality of the multidimensional potential energy surface and the vibrational wavefunctions, it is the representation of the μ-tensor within the Watson Hamiltonian, which has a significant impact on the desired line lists or simulated spectra. Within this work, we studied the dependence of high-resolution rovibrational spectra with respect to the truncation order of the μ-tensor within the rotational contribution and the Coriolis coupling operator of the Watson operator. Moreover, the dependence of the infrared intensities of the rovibrational transitions on an n-mode expansion of the dipole moment surface has been investigated as well. Benchmark calculations are provided for thioformaldehyde, which has already served as a test molecule in other studies and whose rovibrational spectrum was found to be fairly sensitive. All calculations rely on rovibrational configuration interaction theory and the discussed high-order terms of the μ-tensor are a newly implemented feature, whose theoretical basics are briefly discussed.
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Affiliation(s)
- Martin Tschöpe
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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45
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Mendolicchio M, Bloino J, Barone V. Perturb-Then-Diagonalize Vibrational Engine Exploiting Curvilinear Internal Coordinates. J Chem Theory Comput 2022; 18:7603-7619. [PMID: 36322968 DOI: 10.1021/acs.jctc.2c00773] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The present paper is devoted to the implementation and validation of a second-order perturbative approach to anharmonic vibrations, followed by variational treatment of strong couplings (GVPT2) based on curvilinear internal coordinates. The main difference with respect to the customary Cartesian-based formulation is that the kinetic energy operator is no longer diagonal, and has to be expanded as well, leading to additional terms which have to be taken into proper account. It is, however, possible to recast all the equations as well-defined generalizations of the corresponding Cartesian-based counterparts, thus achieving a remarkable simplification of the new implementation. Particular attention is paid to the treatment of Fermi resonances with significant number of test cases analyzed fully, validating the new implementation. The results obtained in this work confirm that curvilinear coordinates strongly reduce the strength of inter-mode couplings compared to their Cartesian counterparts. This increases the reliability of low-order perturbative treatments for semi-rigid molecules and paves the way toward the reliable representation of more flexible molecules where small- and large-amplitude motions can be safely decoupled and treated at different levels of theory.
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Affiliation(s)
- Marco Mendolicchio
- Scuola Superiore Meridionale, Largo S. Marcellino 10, Napoli I-80138, Italy
| | - Julien Bloino
- Scuola Normale Superiore, Piazza dei Cavalieri 7, Pisa I-56126, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, Pisa I-56126, Italy
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46
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Recio P, Alessandrini S, Vanuzzo G, Pannacci G, Baggioli A, Marchione D, Caracciolo A, Murray VJ, Casavecchia P, Balucani N, Cavallotti C, Puzzarini C, Barone V. Intersystem crossing in the entrance channel of the reaction of O( 3P) with pyridine. Nat Chem 2022; 14:1405-1412. [PMID: 36175514 DOI: 10.1038/s41557-022-01047-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 08/25/2022] [Indexed: 01/04/2023]
Abstract
Two quantum effects can enable reactions to take place at energies below the barrier separating reactants from products: tunnelling and intersystem crossing between coupled potential energy surfaces. Here we show that intersystem crossing in the region between the pre-reactive complex and the reaction barrier can control the rate of bimolecular reactions for weakly coupled potential energy surfaces, even in the absence of heavy atoms. For O(3P) plus pyridine, a reaction relevant to combustion, astrochemistry and biochemistry, crossed-beam experiments indicate that the dominant products are pyrrole and CO, obtained through a spin-forbidden ring-contraction mechanism. The experimental findings are interpreted-by high-level quantum-chemical calculations and statistical non-adiabatic computations of branching fractions-in terms of an efficient intersystem crossing occurring before the high entrance barrier for O-atom addition to the N-atom lone pair. At low to moderate temperatures, the computed reaction rates prove to be dominated by intersystem crossing.
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Affiliation(s)
- Pedro Recio
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
| | - Silvia Alessandrini
- Scuola Normale Superiore, Pisa, Italy
- Dipartimento di Chimica 'Giacomo Ciamician', University of Bologna, Bologna, Italy
| | - Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
| | - Giacomo Pannacci
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
| | - Alberto Baggioli
- Dipartimento di Chimica, Materiali e Ingegneria Chimica 'Giulio Natta', Politecnico di Milano, Milan, Italy
| | - Demian Marchione
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
| | - Adriana Caracciolo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - Vanessa J Murray
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
- Montana State University, Bozeman, MT, USA
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Carlo Cavallotti
- Dipartimento di Chimica, Materiali e Ingegneria Chimica 'Giulio Natta', Politecnico di Milano, Milan, Italy.
| | - Cristina Puzzarini
- Dipartimento di Chimica 'Giacomo Ciamician', University of Bologna, Bologna, Italy.
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47
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Yang Q, Bloino J. An Effective and Automated Processing of Resonances in Vibrational Perturbation Theory Applied to Spectroscopy. J Phys Chem A 2022; 126:9276-9302. [DOI: 10.1021/acs.jpca.2c06460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- Qin Yang
- Faculty of Science, Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126Pisa, Italy
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 16610Prague, Czech Republic
| | - Julien Bloino
- Faculty of Science, Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126Pisa, Italy
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48
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Bunn HA, Esselman BJ, Franke PR, Kougias SM, McMahon RJ, Stanton JF, Widicus Weaver SL, Woods RC. Millimeter/Submillimeter-wave Spectroscopy and the Semi-experimental Equilibrium ( reSE) Structure of 1 H-1,2,4-Triazole ( c-C 2H 3N 3). J Phys Chem A 2022; 126:8196-8210. [DOI: 10.1021/acs.jpca.2c06038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Hayley A. Bunn
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53706, United States
| | - Brian J. Esselman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53706, United States
| | - Peter R. Franke
- Department of Chemistry, University of Florida, Gainesville, Florida32611-7200, United States
| | - Samuel M. Kougias
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53706, United States
| | - Robert J. McMahon
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53706, United States
| | - John F. Stanton
- Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, Florida32611-7200, United States
| | | | - R. Claude Woods
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53706, United States
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49
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Falbo E, Fusè M, Lazzari F, Mancini G, Barone V. Integration of Quantum Chemistry, Statistical Mechanics, and Artificial Intelligence for Computational Spectroscopy: The UV-Vis Spectrum of TEMPO Radical in Different Solvents. J Chem Theory Comput 2022; 18:6203-6216. [PMID: 36166322 PMCID: PMC9558374 DOI: 10.1021/acs.jctc.2c00654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Indexed: 11/30/2022]
Abstract
The ongoing integration of quantum chemistry, statistical mechanics, and artificial intelligence is paving the route toward more effective and accurate strategies for the investigation of the spectroscopic properties of medium-to-large size chromophores in condensed phases. In this context we are developing a novel workflow aimed at improving the generality, reliability, and ease of use of the available computational tools. In this paper we report our latest developments with specific reference to unsupervised atomistic simulations employing non periodic boundary conditions (NPBC) followed by clustering of the trajectories employing optimized feature spaces. Next accurate variational computations are performed for a representative point of each cluster, whereas intracluster fluctuations are taken into account by a cheap yet reliable perturbative approach. A number of methodological improvements have been introduced including, e.g., more realistic reaction field effects at the outer boundary of the simulation sphere, automatic definition of the feature space by continuous perception of solute-solvent interactions, full account of polarization and charge transfer in the first solvation shell, and inclusion of vibronic contributions. After its validation, this new approach has been applied to the challenging case of solvatochromic effects on the UV-vis spectra of a prototypical nitroxide radical (TEMPO) in different solvents. The reliability, effectiveness, and robustness of the new platform is demonstrated by the remarkable agreement with experiment of the results obtained through an unsupervised approach characterized by a strongly reduced computational cost as compared to that of conventional quantum mechanics and molecular mechanics models without any accuracy reduction.
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Affiliation(s)
- Emanuele Falbo
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Marco Fusè
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
- Dipartimento
di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Federico Lazzari
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Giordano Mancini
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola
Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy
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50
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Molecular crowding induced loss of native conformation and aggregation of α-chymotrypsinogen A. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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