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Esch BVD, Peters LDM, Sauerland L, Ochsenfeld C. Quantitative Comparison of Experimental and Computed IR-Spectra Extracted from Ab Initio Molecular Dynamics. J Chem Theory Comput 2021; 17:985-995. [PMID: 33512155 DOI: 10.1021/acs.jctc.0c01279] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Experimentally measured infrared spectra are often compared to their computed equivalents. However, the accordance is typically characterized by visual inspection, which is prone to subjective judgment. The primary challenge for a similarity-based analysis is that the artifacts introduced by each approach are very different and, therefore, may require preprocessing steps to determine and correct impeding irregularities. To allow for automated objective assessment, we propose a practical and comprehensive workflow involving scaling factors, a novel baseline correction scheme, and peak smoothing. The resulting spectra can then easily be compared quantitatively using similarity measures, for which we found the Pearson correlation coefficient to be the most suitable. The proposed procedure is then applied to compare the agreement of the experimental infrared spectra from the NIST Chemistry Web book with the calculated spectra using standard harmonic frequency analysis and spectra extracted from ab initio molecular dynamics simulations at different levels of theory. We conclude that the direct, quantitative comparison of calculated and measured IR spectra might become a novel, sophisticated approach to benchmark quantum-chemical methods. In the present benchmark, simulated spectra based on ab initio molecular dynamics show in general better agreement with the experiment than static calculations.
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Affiliation(s)
- Beatriz von der Esch
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, D-81377 München, Germany
| | - Laurens D M Peters
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, D-81377 München, Germany
| | - Lena Sauerland
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, D-81377 München, Germany
| | - Christian Ochsenfeld
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, D-81377 München, Germany
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2
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Nejad A, Crittenden DL. On the separability of large-amplitude motions in anharmonic frequency calculations. Phys Chem Chem Phys 2020; 22:20588-20601. [PMID: 32966420 DOI: 10.1039/d0cp03515g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nuclear vibrational theories based upon the Watson Hamiltonian are ubiquitous in quantum chemistry, but are generally unable to model systems in which the wavefunction can delocalise over multiple energy minima, i.e. molecules that have low-energy torsion and inversion barriers. In a 2019 Chemical Reviews article, Puzzarini et al. note that a common workaround is to simply decouple these problematic modes from all other vibrations in the system during anharmonic frequency calculations. They also point out that this approximation can be "ill-suited", but do not quantify the errors introduced. In this work, we present the first systematic investigation into how separating out or constraining torsion and inversion vibrations within potential energy surface (PES) expansions affects the accuracy of computed fundamental wavenumbers for the remaining vibrational modes, using a test set of 19 tetratomic molecules for which high quality analytic potential energy surfaces and fully-coupled anharmonic reference fundamental frequencies are available. We find that the most effective and efficient strategy is to remove the mode in question from the PES expansion entirely. This introduces errors of up to +10 cm-1 in stretching fundamentals that would otherwise couple to the dropped mode, and ±5 cm-1 in all other fundamentals. These errors are approximately commensurate with, but not necessarily additional to, errors due to the choice of electronic structure model used in constructing spectroscopically accurate PES.
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Affiliation(s)
- Arman Nejad
- Institute of Physical Chemistry, University of Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany.
| | - Deborah L Crittenden
- School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand
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3
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Gallmeier EA, Gallmeier KM, McFarlane J, Morales-Rodriguez ME. Real time monitoring of the chemistry of hydroxylamine nitrate and iron as surrogates for nuclear materials processing. SEP SCI TECHNOL 2019. [DOI: 10.1080/01496395.2019.1606829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Esther A. Gallmeier
- Isotope and Fuel Cycle Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Katharina M. Gallmeier
- Isotope and Fuel Cycle Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Joanna McFarlane
- Isotope and Fuel Cycle Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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Patrick AL, Annesley CJ. Dissociation pathways of protic ionic liquid clusters: Alkylammonium nitrates. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:371-377. [PMID: 30648338 DOI: 10.1002/jms.4329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
Protic ionic liquids are promising candidates for many applications, including as spacecraft propellants. For both fundamental interest and understanding clustering and dissociation during electrospray-based propulsion, it is useful to explore the dissociation pathways of protic ionic liquid clusters, as well as the factors affecting the relative contributions of each pathway to the observed MS/MS spectra. With that said, most of the published reports on ionic liquid cluster dissociation have focused on aprotic ionic liquids. The purpose of the current work is to explore the dissociation pathways (eg, loss of amine, nitric acid, or ion pair) of alkylammonium nitrates using energy-resolved collision-induced dissociation. Here, it was found that, in general, protic ionic liquids have multiple dissociation pathways-namely, protic ionic liquids can lose their neutralized cation (here, an alkylamine) or neutralized anion (here, nitric acid)-in addition to the ion pair dissociation familiar to aprotic salt and aprotic ionic liquid clusters. In general, increasing the basicity of the cation (here, through increasing the degree of alkylation) decreases the propensity to follow these alternative pathways. Interestingly, increasing the cluster size has a similar effect: as cluster size increases, nitric acid loss decreases. These results will help better model and design protic ionic liquids for electrospray-based spacecraft propulsion and help provide a better understanding for the general behavior of protic ionic liquids versus aprotic ionic liquids within mass spectrometers.
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Affiliation(s)
- Amanda L Patrick
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland AFB, Albuquerque, New Mexico
| | - Christopher J Annesley
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland AFB, Albuquerque, New Mexico
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Patrick AL, Vogelhuber KM, Prince BD, Annesley CJ. Theoretical and Experimental Insights into the Dissociation of 2-Hydroxyethylhydrazinium Nitrate Clusters Formed via Electrospray. J Phys Chem A 2018; 122:1960-1966. [PMID: 29382196 DOI: 10.1021/acs.jpca.7b12072] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ionic liquids are used for myriad applications, including as catalysts, solvents, and propellants. Specifically, 2-hydroxyethylhydrazinium nitrate (HEHN) has been developed as a chemical propellant for space applications. The gas-phase behavior of HEHN ions and clusters is important in understanding its potential as an electrospray thruster propellant. Here, the unimolecular dissociation pathways of two clusters are experimentally observed, and theoretical modeling of hydrogen bonding and dissociation pathways is used to help rationalize those observations. The cation/deprotonated cation cluster [HEH2 - H]+, which is observed from electrospray ionization, is calculated to be considerably more stable than the complementary cation/protonated anion adduct, [HEH + HNO3]+, which is not observed experimentally. Upon collisional activation, a larger cluster [(HEHN)2HEH]+ undergoes dissociation via loss of nitric acid at lower collision energies, as predicted theoretically. At higher collision energies, additional primary and secondary loss pathways open, including deprotonated cation loss, ion-pair loss, and double-nitric-acid loss. Taken together, these experimental and theoretical results contribute to a foundational understanding of the dissociation of protic ionic liquid clusters in the gas phase.
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Affiliation(s)
- Amanda L Patrick
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base , New Mexico 87117, United States
| | - Kristen M Vogelhuber
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base , New Mexico 87117, United States.,Institute for Scientific Research, Boston College , Chestnut Hill, Massachusetts 02467, United States
| | - Benjamin D Prince
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base , New Mexico 87117, United States
| | - Christopher J Annesley
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base , New Mexico 87117, United States
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6
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Peters LDM, Kussmann J, Ochsenfeld C. Efficient and Accurate Born-Oppenheimer Molecular Dynamics for Large Molecular Systems. J Chem Theory Comput 2017; 13:5479-5485. [PMID: 29068678 DOI: 10.1021/acs.jctc.7b00937] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An efficient scheme for the calculation of Born-Oppenheimer molecular dynamics (BOMD) simulations is introduced. It combines the corrected small basis set Hartree-Fock (HF-3c) method by Sure and Grimme [J. Comput. Chem. 2013, 43, 1672], extended Lagrangian BOMD (XL-BOMD) by Niklasson et al. [J. Chem. Phys. 2009, 130, 214109], and the calculation of the two electron integrals on graphics processing units (GPUs) [J. Chem. Phys. 2013, 138, 134114; J. Chem. Theory Comput. 2015, 11, 918]. To explore the parallel performance of our strong scaling implementation of the method, we present timings and extract, as its validation and first illustrative application, high-quality vibrational spectra from simulated trajectories of β-carotene, paclitaxel, and liquid water (up to 500 atoms). We conclude that the presented BOMD scheme may be used as a cost-efficient and reliable tool for computing vibrational spectra and thermodynamics of large molecular systems including explicit solvent molecules containing 500 atoms and more. Simulating 50 ps of maitotoxin (nearly 500 atoms) employing time steps of 0.5 fs requires ∼3 weeks on 12 CPUs (Intel Xeon E5 2620 v3) with 24 GPUs (AMD FirePro 3D W8100).
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Affiliation(s)
- Laurens D M Peters
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU) , Butenandtstr. 7, D-81377 München, Germany.,Center for Integrated Protein Science (CIPSM) at the Department of Chemistry, University of Munich (LMU) , Butenandtstr. 5-13, D-81377 München, Germany
| | - Jörg Kussmann
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU) , Butenandtstr. 7, D-81377 München, Germany.,Center for Integrated Protein Science (CIPSM) at the Department of Chemistry, University of Munich (LMU) , Butenandtstr. 5-13, D-81377 München, Germany
| | - Christian Ochsenfeld
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU) , Butenandtstr. 7, D-81377 München, Germany.,Center for Integrated Protein Science (CIPSM) at the Department of Chemistry, University of Munich (LMU) , Butenandtstr. 5-13, D-81377 München, Germany
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Brehm M, Thomas M. Computing Bulk Phase Raman Optical Activity Spectra from ab initio Molecular Dynamics Simulations. J Phys Chem Lett 2017; 8:3409-3414. [PMID: 28685571 DOI: 10.1021/acs.jpclett.7b01616] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present our novel methodology for computing Raman optical activity (ROA) spectra of liquid systems from ab initio molecular dynamics (AIMD) simulations. The method is built upon the recent developments to obtain magnetic dipole moments from AIMD and to integrate molecular properties by using radical Voronoi tessellation. These techniques are used to calculate optical activity tensors for large and complex periodic bulk phase systems. Only AIMD simulations are required as input, and no time-consuming perturbation theory is involved. The approach relies only on the total electron density in each time step and can readily be combined with a wide range of electronic structure methods. To the best of our knowledge, these are the first computed ROA spectra for a periodic bulk phase system. As an example, the experimental ROA spectrum of liquid (R)-propylene oxide is reproduced very well.
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Affiliation(s)
- Martin Brehm
- Institut für Chemie - Theoretische Chemie, Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Martin Thomas
- Institut für Chemie - Theoretische Chemie, Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
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Thomas M, Brehm M, Fligg R, Vöhringer P, Kirchner B. Computing vibrational spectra from ab initio molecular dynamics. Phys Chem Chem Phys 2013; 15:6608-22. [DOI: 10.1039/c3cp44302g] [Citation(s) in RCA: 319] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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9
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Cagnina S, Rotureau P, Fayet G, Adamo C. The ammonium nitrate and its mechanism of decomposition in the gas phase: a theoretical study and a DFT benchmark. Phys Chem Chem Phys 2013; 15:10849-58. [DOI: 10.1039/c3cp50368b] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Alavi S, Taghikhani M. Proton exchange in acid–base complexes induced by reaction coordinates with heavy atom motions. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Abstract
Hildenbrand and co-workers have shown recently that the vapor above solid ammonium nitrate includes molecules of NH₄NO₃, not only NH₃ and HNO₃ as previously believed. Their measurements led to thermochemical values that imply an enthalpy change of D₂₉₈ = 98 ± 9 kJ mol⁻¹ for the gas-phase dissociation of ammonium nitrate into NH₃ and HNO₃. Using updated spectroscopic information for the partition function leads to the revised value of D₂₉₈ = 78 ± 21 kJ mol⁻¹ (accompanying paper in this journal, Hildenbrand, D. L., Lau, K. H., and Chandra, D. J. Phys. Chem. B 2010, DOI: 10.1021/jp105773q). In contrast, high-level ab initio calculations, detailed in the present report, predict a dissociation enthalpy half as large as the original result, 50 ± 3 kJ mol⁻¹. These are frozen-core CCSD(T) calculations extrapolated to the limiting basis set aug-cc-pV∞Z using an anharmonic vibrational partition function and a variational treatment of the NH₃ rotor. The corresponding enthalpy of formation is Δ(f)H₂₉₈°(NH₄NO₃,g) = −230.6 ± 3 kJ mol⁻¹. The origin of the disagreement with experiment remains unexplained.
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Affiliation(s)
- Karl K Irikura
- Chemical and Biochemical Reference Data Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8320, USA
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Hildenbrand DL, Lau KH, Chandra D. Revised Thermochemistry of Gaseous Ammonium Nitrate, NH4NO3(g). J Phys Chem A 2010; 114:11654-5. [DOI: 10.1021/jp105773q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D. L. Hildenbrand
- SRI International, Menlo Park, California 94025, United States, and Metallurgical and Materials Engineering, University of Nevada, Reno, Nevada 89557, United States
| | - K. H. Lau
- SRI International, Menlo Park, California 94025, United States, and Metallurgical and Materials Engineering, University of Nevada, Reno, Nevada 89557, United States
| | - D. Chandra
- SRI International, Menlo Park, California 94025, United States, and Metallurgical and Materials Engineering, University of Nevada, Reno, Nevada 89557, United States
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Deb N, Tiwary AS, Mukherjee AK. Calculation of the Kirkwood–Frohlich correlation factor and dielectric constant of methanol using a statistical model and density functional theory. Mol Phys 2010. [DOI: 10.1080/00268976.2010.497776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Martín-Llorente B, Fernández-Torre D, Escribano R. Theoretical study on hydrogen-bond effects in IR spectra of high- and low-temperature phases of nitric acid dihydrate. Chemphyschem 2009; 10:3229-38. [PMID: 19852014 DOI: 10.1002/cphc.200900446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The low- and high-temperature phases (alpha and beta, respectively) of solid nitric acid dihydrate (NAD) are studied in depth by DFT methods. Each phase contains two types of complex structures (H(3)O(+)) x (H(2)O), designated A and B, with different hydrogen-bonding (HB) characteristics. The theoretical study reveals that type A complexes are weakly bound and could be described as (H(3)O)(+) and H(2)O aggregates, with decoupled vibrational modes, whereas in type B structures the proton is situated close to the centre of the O...O bond and induces strong vibrational coupling. The proton-transfer mode is predicted at quite different wavenumbers in each complex, which provides an important differentiating spectral feature, together with splitting of some bands in beta-NAD. Theoretical spectra are estimated by using two GGA parameterizations, namely, PBE and BLYP. The potential-energy surface for each type of HB in NAD is also studied, as is the spectral influence of displacement of the shared H atom along the O-O bond. The results are compared to literature infrared spectra recorded by different techniques, namely, transmission and reflection-absorption, with both normal and tilted incident radiation. This work provides a thorough assignment of the observed spectra, and predictions for some spectra not yet available. The usefulness of high-level theoretical calculations as performed herein to discriminate between two phases of a solid crystal is thus evidenced.
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Torrent-Sucarrat M, Anglada JM, Luis JM. Role of vibrational anharmonicity in atmospheric radical hydrogen-bonded complexes. Phys Chem Chem Phys 2009; 11:6377-88. [DOI: 10.1039/b904736k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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