1
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Watrous AG, Fortenberry RC. The fundamental vibrational frequencies and spectroscopic constants of the C 2O 2H 2 isomers: molecules known in simulated interstellar ice analogues. Phys Chem Chem Phys 2024; 26:21260-21269. [PMID: 39076036 DOI: 10.1039/d4cp02201g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/31/2024]
Abstract
While trans-glyoxal may not be easily observable in astronomical sources through either IR or radioastronomy due to its C2h symmetry, its cis conformer along with the cyc-H2COCO epoxide isomer should be ready targets for astrochemical detection. The present quantum chemical study shows that not only are both molecular isomers strongly polar, they also have notable IR features and low isomerisation energies of 4.1 kcal mol-1 and 10.7 kcal mol-1, respectively. These three isomers along with two other C2O2H2 isomers have had their full set of fundamental vibrational frequencies and spectroscopic constants characterised herein. These isomers have previously been shown to occur in simulated astrophysical ices making them worthy targets of astronomical search. Furthermore, the hybrid quartic force field (QFF) approach utilized herein to produce the needed spectral data has a mean absolute percent error compared to the experimentally-available, gas phase fundamental vibrational frequencies of 0.6% and rotational constants to better than 0.1%. The hybrid QFF is defined from explicitly correlated coupled cluster theory at the singles, doubles, and perturbative triples level [CCSD(T)-F12b] including core electron correlation and a canonical CCSD(T) relativity correction for the harmonic (quadratic) terms in the QFF and simple CCSD(T)-F12b/cc-pVDZ energies for the cubic and quartic terms, the so-called "F12-TcCR+DZ QFF." This method is producing spectroscopically-accurate predictions for both fundamental vibrational frequencies and principal spectroscopic constants. Hence, the values computed in this work should be notably accurate and, hence, exceptionally useful to the spectroscopy and astrochemistry communities.
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2
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Fortenberry RC. Picking up Good Vibrations through Quartic Force Fields and Vibrational Perturbation Theory. J Phys Chem Lett 2024; 15:6528-6537. [PMID: 38875074 DOI: 10.1021/acs.jpclett.4c01089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Quartic force fields (QFFs) define sparse potential energy surfaces (compared to semiglobal surfaces) that are the cheapest and easiest means of computing anharmonic vibrational frequencies, especially when utilized with second-order vibrational perturbation theory (VPT2). However, flat and shallow potential surfaces are exceedingly difficult for QFFs to treat through a combination of numerical noise in the often numerically computed derivatives and in competing energy factors in the composite energies often utilized to provide high-level spectroscopic predictions. While some of these issues can be alleviated with analytic derivatives, hybrid QFFs, and intelligent choices in coordinate systems, the best practice is for predicting good molecular vibrations via QFFs is to understand what they cannot do, and this manuscript documents such cases where QFFs may fail.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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3
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Firth RA, Palmer CZ, Francisco JS, Fortenberry RC. Rovibrational analysis of AlCO3, OAlO2, and HOAlO2 for possible atmospheric detection. J Chem Phys 2024; 160:214304. [PMID: 38832738 DOI: 10.1063/5.0212147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 05/19/2024] [Indexed: 06/05/2024] Open
Abstract
The lack of observational data for the AlO molecule in the mesosphere/lower thermosphere may be due to ablated aluminum reacting quickly to form other species. Previously proposed reaction pathways show that aluminum could be ablated in the atmosphere from meteoritic activity, but there currently exist very limited spectroscopic data on the intermediates in these reactions, limiting the possible detection of said molecules. As such, rovibrational spectroscopic data are computed herein using quartic force field methodology at four different levels of theory for the neutral intermediates AlCO3, OAlO2, and HOAlO2. Each molecule exhibits multiple vibrational modes with large vibrational transition intensities. For instance, the C-O stretch (ν1) in AlCO3 has a harmonic intensity of 536 km mol-1, the Al-O stretch (ν2) in OAlO2 has an intensity of 678 km mol-1, and the out-of-plane torsion (ν9) in HOAlO2 has an intensity of 158 km mol-1. All three molecules have exceptionally large dipole moments of 6.27, 4.21, and 5.04 D, respectively. These properties indicate that all three molecules are good candidates for potential atmospheric observation utilizing vibrational and/or rotational spectroscopic techniques.
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Affiliation(s)
- Rebecca A Firth
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, USA
| | - C Zachary Palmer
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, USA
| | - Joseph S Francisco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6243, USA
| | - Ryan C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, USA
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4
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Flint AR, Westbrook BR, Fortenberry RC. Theoretical Rotational and Vibrational Spectral Data for the Hypermagnesium Oxide Species Mg 2O and Mg 2O . Chemphyschem 2024:e202400479. [PMID: 38801234 DOI: 10.1002/cphc.202400479] [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: 04/26/2024] [Revised: 05/22/2024] [Accepted: 05/26/2024] [Indexed: 05/29/2024]
Abstract
While magnesium is astronomically observed in small molecules, it largely serves as a contributor to silicate grains, though how these grains form is not well-understood. The smallest hypermagnesium oxide compounds (Mg2 ${{}_{2}}$ O/Mg2 ${{}_{2}}$ O+ ${{}^{+}}$ ) may play a role in silicate formation, but little vibrational reference data exist. As such, anharmonic spectroscopic data are computed forX ˜ 1 Σ g + ${{{\tilde{\rm {X}}}}^1 {\rm{\Sigma }}_g^+ }$ Mg2 ${{}_{2}}$ O,a ˜ 1 Σ u + ${{{\tilde{\rm {a}}}}^1 {\rm{\Sigma }}_u^+ }$ Mg2 ${{}_{2}}$ O, andX ˜ 2 Σ g + ${{{\tilde{\rm {X}}}}^2 {\rm{\Sigma }}_g^+ }$ Mg2 ${{}_{2}}$ O+ ${{}^{+}}$ using quartic force fields (QFFs). Explicitly-correlated coupled-cluster QFFs for the neutral species perform well, implying that full multireference treatment may not be necessary for such systems if enough electron correlation is included. Equation-of-motion ionization potential (EOMIP) methods forX ˜ 2 Σ g + ${{{\tilde{\rm {X}}}}^2 {\rm{\Sigma }}_g^+ }$ Mg2 ${{}_{2}}$ O+ ${{}^{+}}$ QFFs circumvent previous symmetry breaking issues even in explicitly-correlated coupled-cluster results, motivating the need for EOMIP treatments at minimum for such systems. All three species are found to have high-intensity vibrational frequencies. Even so, the highly intense frequency (X ˜ 1 Σ g + ${{{\tilde{\rm {X}}}}^1 {\rm{\Sigma }}_g^+ }$ Mg2 ${{}_{2}}$ O: 894.7 cm-1/11.18 μm;a ˜ 1 Σ u + ${{{\tilde{\rm {a}}}}^1 {\rm{\Sigma }}_u^+ }$ Mg2 ${{}_{2}}$ O: 915.0 cm-1/10.91 μm) for either neutral state may be astronomically obscured by the polycyclic aromatic hydrocarbon 11.2 μm band. Mg2 ${{}_{2}}$ O+ ${{}^{+}}$ may be less susceptible to such obfuscation, and itsν 1 ${{\nu }_{1}}$ intensity is computed to be a massive 4793 km mol-1.
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Affiliation(s)
- Athena R Flint
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS 38655, USA
| | - Brent R Westbrook
- The Open Force Field Initiative, Open Molecular Software Foundation, Davis, CA 95616, USA
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS 38655, USA
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5
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Fortenberry RC. Quantum Chemistry and Astrochemistry: A Match Made in the Heavens. J Phys Chem A 2024; 128:1555-1565. [PMID: 38381079 DOI: 10.1021/acs.jpca.3c07601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Quantum chemistry can uniquely answer astrochemical questions that no other technique can provide. Computations can be parallelized, automated, and left to run continuously providing exceptional molecular throughput that cannot be done through experimentation. Additionally, the granularity of the individual computations that are required of potential energy surfaces, reaction mechanism pathways, or other quantum chemically derived observables produces a unique mosaic that make up the larger whole. These pieces can be dissected for their individual contributions or evaluated in an ad hoc fashion for each of their roles in generating the larger whole. No other scientific approach is capable of reporting such fine-grained insights. Quantum chemistry also works from a bottom-up approach in providing properties directly from the desired molecule instead of a top-down perspective as required of experiment where molecules have to be linked to observed phenomena. Furthermore, modern quantum chemistry is well within the range of "chemical accuracy" and is approaching "spectroscopic accuracy." As such, the seemingly difficult questions asked by astrochemistry that would not be asked initially for any other application require quantum chemical reference data. While the results of quantum chemical computations are needed to interpret astrochemical observation, modeling, or laboratory experimentation, such hard questions, regardless of the original need to answer them, produce unique solutions. While questions in astrochemistry often require novel developments in and implementations of quantum chemistry as outlined herein, the applications of these solutions will stretch beyond astrochemistry and may yet impact fields much closer to Earth.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, Oxford, Mississippi 38677-1848, United States
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6
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Esposito VJ, Palmer CZ, Fortenberry RC, Francisco JS. Spectroscopy and Photochemistry of OAlNO and Implications for New Metal Chemistry in the Atmosphere. J Phys Chem A 2023; 127:7618-7629. [PMID: 37647609 DOI: 10.1021/acs.jpca.3c04437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
A new aluminum-bearing species, OAlNO, which has the potential to impact the chemistry of the Earth's upper atmosphere, is characterized via high-level, ab initio, spectroscopic methods. Meteor-ablated aluminum atoms are quickly oxidized to aluminum oxide (AlO) in the mesosphere and lower thermosphere (MLT), where a steady-state layer of AlO then builds up. Concurrent formation of nitric oxide (NO) in the same region of the atmosphere will lead to the bimolecular formation of the OAlNO molecule. Molecular orbital analysis provides fundamental insights into the chemical bonding and energetic arrangement of the triplet (1 3A″) ground state and singlet (1 1A') excited-state species of OAlNO. Additionally, unpaired electrons on the terminal oxygen atom of triplet (1 3A″) OAlNO cause it to be reactive to atmospheric species, potentially impacting climate science and high-altitude chemistry. The triplet (1 3A″) ground-state species exhibits a large permanent dipole moment useful for rotational spectroscopic detection; however, similar rotational constants to the singlet (1 1A') excited-state species will hamper differentiation in a spectrum. Strong infrared intensities will assist in detection and discrimination of the different spin states and isomers. Repulsive electronic excited states of OAlNO will lead to photolysis of the Al-N bond and formation of various electronic states of AlO + NO through nonadiabatic pathways. Reaction through the OAlNO intermediate represents a means for the production of electronically excited AlO, leading to new chemistry in the atmosphere. Excitation to higher-lying electronic states will lead to fluorescence with a minor Stokes shift, useful for laboratory investigation. Such physical properties of this molecule will allow for new, unexplored chemical pathways in the MLT to be considered.
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Affiliation(s)
- Vincent J Esposito
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6243, United States
| | - C Zachary Palmer
- Department of Chemistry and Biochemistry, University of Mississippi, University Park, Mississippi 38677-1848, United States
| | - Ryan C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University Park, Mississippi 38677-1848, United States
| | - Joseph S Francisco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6243, United States
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7
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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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Tan JA, Barbarona RF, Kuo JL. Approaching the "Zundel" Limit: Tuning the Vibrational Coupling in N 2H +Ng, Ng = {He, Ne, Ar, Kr, Xe, and Rn}. J Phys Chem A 2023. [PMID: 37418837 DOI: 10.1021/acs.jpca.3c01956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
The diazenylium ion (N2H+) is a ubiquitous ion in dense molecular clouds. This ion is often used as a dense gas tracer in outer space. Most of the previous works on diazenylium ion have focused on the shared-proton stretch band, νH+. In this work, we have performed reduced-dimensional calculations to investigate the vibrational structure of N2H+Ng, Ng = {He, Ne, Ar, Kr, Xe, and Rn}. We demonstrate a few interesting things about this system. First, the vibrational coupling in N2H+ can be tuned to switch on interesting anharmonic effects such as Fermi resonance or combination bands by tagging it with different noble gases. Second, a comparison of the vibrational spectrum from N2H+He to N2H+Rn shows that the νH+ can be swept from an "Eigen-like" to a "Zundel-like" limiting case. Anharmonic calculations were performed using a multilevel approach, which utilized the MP2 and CCSD(T) levels of theories. Binding energies for the elimination of Ng in N2H+Ng are also reported.
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Affiliation(s)
- Jake A Tan
- Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan
| | - Rona F Barbarona
- Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan
- Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
- Department of Physics, National Central University, Taoyuan 32001, Taiwan
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan
- Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
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9
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Wang Y, Chen Z, Yang Y. Calculating Vibrational Excited State Absorptions with Excited State Constrained Minimized Energy Surfaces. J Phys Chem A 2023. [PMID: 37335973 DOI: 10.1021/acs.jpca.3c01420] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
The modeling and interpretation of vibrational spectra are crucial for studying reaction dynamics using vibrational spectroscopy. Most prior theoretical developments focused on describing fundamental vibrational transitions while fewer developments focused on vibrational excited state absorptions. In this study, we present a new method that uses excited state constrained minimized energy surfaces (CMESs) to describe vibrational excited state absorptions. The excited state CMESs are obtained similarly to the previous ground state CMES development in our group but with additional wave function orthogonality constraints. Using a series of model systems, including the harmonic oscillator, Morse potential, double-well potential, quartic potential, and two-dimensional anharmonic potential, we demonstrate that this new procedure provides good estimations of the transition frequencies for vibrational excited state absorptions. These results are significantly better than those obtained from harmonic approximations using conventional potential energy surfaces, demonstrating the promise of excited state CMES-based methods for calculating vibrational excited state absorptions in real systems.
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Affiliation(s)
- Yiwen Wang
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Zehua Chen
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Yang Yang
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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10
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Agbaglo DA, Cheng Q, Fortenberry RC, Stanton JF, DeYonker NJ. Theoretical Rovibrational Spectroscopy of Magnesium Tricarbide-Multireference Character Thwarts a Full Analysis of All Isomers. J Phys Chem A 2022; 126:4132-4146. [PMID: 35758849 DOI: 10.1021/acs.jpca.2c01340] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Magnesium tricarbide isomers are studied herein with coupled cluster theory and multireference configuration interaction to support their possible detection in astrochemical environments such as the circumstellar envelope surrounding the star IRC +10216 or in terrestrial laboratories. Magnesium-bearing species may abound in the interstellar medium (ISM), but only eight (MgNC, MgCN, HMgNC, MgC2H, MgC3N, MgC4H, MgC5N, and MgC6H) have been directly identified thus far. Several possible isomers for the related MgC3 system are explored in their singlet and triplet spin multiplicities. Overall, this work offers quantum chemical insight of rovibrational spectroscopic data for MgC3 using quartic force fields (QFFs) based on the CCSD(T) and CCSD(T)-F12 levels of theory at the complete basis set (CBS) limit. Additional corrections with small basis set CCSDT(Q) and scalar relativistic effects are also included in the analysis. Salient multireference character is found in the singlet diamond electronic state, which makes a definitive assignment of the ground state challenging. Nevertheless, coupled cluster-based composite energies and multireference configuration interaction both predict that the 1A1 diamond isomer is 1.6-2.2 kcal mol-1 lower in energy than the 3A1 diamond isomer. Furthermore, highly accurate binding energies of various isomers MgC3 are provided for comparison to photodetachment experiments. Dipole moments along with harmonic infrared intensities will guide efforts for astronomical and spectroscopic characterization.
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Affiliation(s)
- Donatus A Agbaglo
- Department of Chemistry, University of Memphis, Memphis, Tennessee 38151, United States
| | - Qianyi Cheng
- Department of Chemistry, University of Memphis, Memphis, Tennessee 38151, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - John F Stanton
- Department of Chemistry and Physics, University of Florida, Gainesville, Florida 32611, United States
| | - Nathan J DeYonker
- Department of Chemistry, University of Memphis, Memphis, Tennessee 38151, United States
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Spectral Signatures of Hydrogen Thioperoxide (HOSH) and Hydrogen Persulfide (HSSH): Possible Molecular Sulfur Sinks in the Dense ISM. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27103200. [PMID: 35630675 PMCID: PMC9143799 DOI: 10.3390/molecules27103200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/02/2022] [Accepted: 05/05/2022] [Indexed: 11/17/2022]
Abstract
For decades, sulfur has remained underdetected in molecular form within the dense interstellar medium (ISM), and somewhere a molecular sulfur sink exists where it may be hiding. With the discovery of hydrogen peroxide (HOOH) in the ISM in 2011, a natural starting point may be found in sulfur-bearing analogs that are chemically similar to HOOH: hydrogen thioperoxide (HOSH) and hydrogen persulfide (HSSH). The present theoretical study couples the accuracy in the anharmonic fundamental vibrational frequencies from the explicitly correlated coupled cluster theory with the accurate rotational constants provided by canonical high-level coupled cluster theory to produce rovibrational spectra for use in the potential observation of HOSH and HSSH. The ν6 mode for HSSH at 886.1 cm−1 is within 0.2 cm−1 of the gas-phase experiment, and the B0 rotational constant for HSSH of 6979.5 MHz is within 9.0 MHz of the experimental benchmarks, implying that the unknown spectral features (such as the first overtones and combination bands) provided herein are similarly accurate. Notably, a previous experimentally-attributed 2ν1 mode, at 7041.8 cm−1, has been reassigned to the ν1+ν5 combination band based on the present work’s ν1+ν5 value at 7034.3 cm−1. The most intense vibrational transitions for each molecule are the torsions, with HOSH having a more intense transition of 72 km/mol compared to HSSH’s intensity of 14 km/mol. Furthermore, HOSH has a larger net dipole moment of 1.60 D compared to HSSH’s 1.15 D. While HOSH may be the more likely candidate of the two for possible astronomical observation via vibrational spectroscopy due to the notable difference in their intensities, both HSSH and HOSH have large enough net dipole moments to be detectable by rotational spectroscopy to discover the role these molecules may have as possible molecular sulfur sinks in the dense ISM.
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Roy TK. Performance of Vibrational Self-Consistent Field Theory for Accurate Potential Energy Surfaces: Fundamentals, Excited States, and Intensities. J Phys Chem A 2022; 126:608-622. [PMID: 35050620 DOI: 10.1021/acs.jpca.1c09989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The performance of vibrational structure calculations beyond harmonic approximation in the framework of the vibrational self-consistent field method with second-order perturbation corrections (VSCF-PT2) is investigated in conjunction with very accurate potential energy surfaces (PESs) given by various coupled-cluster electronic structure theories. The quality of anharmonic calculations depends on the accuracy of the underlying multidimensional PES obtained from its functional form, which is given by the level of electronic structure theory. Two such highest levels of typical coupled-cluster electronic structure methods, CCSD and the ″gold standard″ CCSD(T), along with their variants such as CCD, CR-CCL (completely renormalized CR-CC(2,3) approach), and CCSD(TQ) are tested for the construction of accurate anharmonic potentials without any fitting or ad hoc scaling and using cc-pVTZ basis sets. The accuracy of VSCF-PT2 theory in comparison to experimental values is tested for a series of 16 molecules with 135 fundamental bands, 64 overtones, and combination bands and also for 39 intensities. It is found that CCD and CCSD bind the potential tighter than CCSD(T) and the computed VSCF-PT2 transitions are more blue-shifted showing higher deviation from the experiment. In general, VSCF-PT2 results computed at the CCSD(T) potential offer a good cost/accuracy ratio, with the mean absolute deviation and the mean absolute percentage error with the experiment being ∼16 cm-1 and 1.38, respectively, for fundamentals. Additionally, while the CR-CCL and CCSD(TQ) methods offer similar levels of accuracies as compared to CCSD(T), the former offers a better accuracy/cost ratio than the latter and is a suitable alternative to CCSD(T).
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Affiliation(s)
- Tapta Kanchan Roy
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), Samba, Jammu and Kashmir 181143, India
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13
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Westbrook B, Beasley G, Fortenberry RC. Polycyclic Aliphatic Hydrocarbons: Is Tetrahedrane Present in UIR Spectra? Phys Chem Chem Phys 2022; 24:14348-14353. [DOI: 10.1039/d2cp01103d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The smallest Platonic hydrocarbon, tetrahedrane, has been subject to frequent theoretical and experimental study for 50 years, but its infrared spectrum and synthetic pathway remain a mystery. The recent partial...
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14
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Westbrook BR, Fortenberry RC. Anharmonic Vibrational Frequencies of Water Borane and Associated Molecules. Molecules 2021; 26:molecules26237348. [PMID: 34885929 PMCID: PMC8658819 DOI: 10.3390/molecules26237348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 12/03/2022] Open
Abstract
Water borane (BH3OH2) and borinic acid (BH2OH) have been proposed as intermediates along the pathway of hydrogen generation from simple reactants: water and borane. However, the vibrational spectra for neither water borane nor borinic acid has been investigaged experimentally due to the difficulty of isolating them in the gas phase, making accurate quantum chemical predictions for such properties the most viable means of their determination. This work presents theoretical predictions of the full rotational and fundamental vibrational spectra of these two potentially application-rich molecules using quartic force fields at the CCSD(T)-F12b/cc-pCVTZ-F12 level with additional corrections included for the effects of scalar relativity. This computational scheme is further benchmarked against the available gas-phase experimental data for the related borane and HBO molecules. The differences are found to be within 3 cm−1 for the fundamental vibrational frequencies and as close as 15 MHz in the B0 and C0 principal rotational constants. Both BH2OH and BH3OH2 have multiple vibrational modes with intensities greater than 100 km mol−1, namely ν2 and ν4 in BH2OH, and ν1, ν3, ν4, ν9, and ν13 in BH3OH2. Finally, BH3OH2 has a large dipole moment of 4.24 D, which should enable it to be observable by rotational spectroscopy, as well.
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15
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Westbrook BR, Patel DJ, Dallas JD, Swartzfager GC, Lee TJ, Fortenberry RC. Fundamental Vibrational Frequencies and Spectroscopic Constants of Substituted Cyclopropenylidene (c-C 3HX, X = F, Cl, CN). J Phys Chem A 2021; 125:8860-8868. [PMID: 34609881 DOI: 10.1021/acs.jpca.1c06576] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The recent detection of ethynyl-functionalized cyclopropenylidene (c-C3HC2H) has initiated the search for other functional forms of cyclopropenylidene (c-C3H2) in space. There is existing gas-phase rotational spectroscopic data for cyano-cyclopropenylidene (c-C3HCN), but the present work provides the first anharmonic vibrational spectral data for that molecule, as well as the first full set of both rotational and vibrational spectroscopic data for fluoro- and chloro-cyclopropenylidenes (c-C3HF and c-C3HCl). All three molecules have fundamental vibrational frequencies with substantial infrared intensities. Namely, c-C3HCN has a moderately intense fundamental frequency at 1244.4 cm-1, while c-C3HF has two large intensity modes at 1765.4 and 1125.3 cm-1 and c-C3HCl again has two large intensity modes at 1692.0 and 1062.5 cm-1. All of these frequencies are well within the spectral range covered by the high-resolution EXES instrument on NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA). Further, all three molecules have dipole moments of around 3.0 D in line with c-C3H2, enabling them to be observed by pure rotational spectroscopy, as well. Thus, the rovibrational spectral data presented herein should assist with future laboratory studies of functionalized cyclopropenylidenes and may lead to their interstellar or circumstellar detection.
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Affiliation(s)
- Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Dev J Patel
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Jax D Dallas
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - G Clark Swartzfager
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States.,Cleveland Central High School, 300 West Sunflower Road, Cleveland, Mississippi 38732, United States
| | - Timothy J Lee
- MS 245-3, NASA Ames Research Center, Moffett Field, California 94035, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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16
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Fortenberry RC, Francisco JS. Anharmonic fundamental vibrational frequencies and spectroscopic constants of the potential HSO 2 radical astromolecule. J Chem Phys 2021; 155:114301. [PMID: 34551550 DOI: 10.1063/5.0062560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The recent report that HSO2 is likely kinetically favored over the HOSO thermodynamic product in hydrogen addition to sulfur dioxide in simulated Venusian atmospheric conditions has led to the need for reference rotational, vibrational, and rovibrational spectral data for this molecule. While matrix-isolation spectroscopy has been able to produce vibrational frequencies for some of the vibrational modes, the full infrared to microwave spectrum of 1 2A' HSO2 is yet to be generated. High-level quantum chemical computations show in this work that the >2.5 D dipole moment of this radical makes it a notable target for possible radioastronomical observation. Additionally, the high intensity antisymmetric S-O stretch is computed here to be 1298.3 cm-1, a 13.9 cm-1 blueshift up from H2 matrix analysis. In any case, the full set of rotational and spectroscopic constants and anharmonic fundamental vibrational frequencies is provided in this work in order to help characterize HSO2 and probe its kinetic favorability.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677-1848, USA
| | - Joseph S Francisco
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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17
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Barone V, Alessandrini S, Biczysko M, Cheeseman JR, Clary DC, McCoy AB, DiRisio RJ, Neese F, Melosso M, Puzzarini C. Computational molecular spectroscopy. ACTA ACUST UNITED AC 2021. [DOI: 10.1038/s43586-021-00034-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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18
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Gardner MB, Westbrook BR, Fortenberry RC, Lee TJ. Highly-accurate quartic force fields for the prediction of anharmonic rotational constants and fundamental vibrational frequencies. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 248:119184. [PMID: 33293226 DOI: 10.1016/j.saa.2020.119184] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 06/12/2023]
Abstract
The CcCR quartic force field (QFF) methodology is capable of computing B0 and C0 rotational constants to within 35 MHz (0.14%) of experiment for triatomic and larger molecules with at least two heavy atoms. Additionally, the same constants for molecules with four or more atoms agree to within 20 MHz (0.12%) of experiment for the current test set. This work also supports previous claims that the same QFF methodology can produce fundamental vibrational frequencies with a deviation less than 5.7 cm-1 from experiment. Consequently, this approach of augmenting complete basis set extrapolated energies with treatments of core electron correlation and scalar relativity produces some of the most accurate rovibrational spectroscopic data available.
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Affiliation(s)
- Mason B Gardner
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS 38677-1848, United States
| | - Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS 38677-1848, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS 38677-1848, United States.
| | - Timothy J Lee
- MS 245-3, NASA Ames Research Center, Moffett Field, CA 94035, United States
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19
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Fortenberry RC, DeYonker NJ. Rovibrational Quantum Chemical Treatment of Inorganic and Organometallic Astrochemicals. Acc Chem Res 2021; 54:271-279. [PMID: 33356121 DOI: 10.1021/acs.accounts.0c00631] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ConspectusOur two groups have both independently and collaboratively been pushing quantum-chemical techniques to produce highly accurate predictions of anharmonic vibrational frequencies and spectroscopic constants for molecules containing atoms outside of the typical upper p block. Methodologies employ composite approaches, relying on various levels of coupled cluster theory-most often at the singles, doubles, and perturbative triples level-and quartic force field constructions of the potential portion of the intramolecular Watson Hamiltonian. Such methods are known to perform well for organic species, and we have extended this to molecules containing atoms outside of this realm.One notable atom that has received much attention in this application is magnesium. Mg is the second-most-abundant element in the Earth's mantle, and while molecules containing this element are among the confirmed astrochemicals, its further atomic abundance in the galaxy implies that many more molecules (both purely inorganic and organometallic) containing element 12 exist in astrophysical regions in chemical sizes between those of atoms and dust-sized nanocrystals. Our approach discussed herein is producing quality benchmarks and predicting novel data for magnesium-bearing molecules.The story is similar for Al and Si, which are also notably abundant in both rocky bodies and the universe at large. While Na, Sc, and Cu may not be as abundant as Mg, Al, and Si, molecules containing Na and transition metals have also previously been reported to be detected beyond the Earth. Consequently, the need to produce spectral reference data for molecules containing such atoms is growing. While several experimental groups (including, notably, the groups in Arizona, Boston, and France/Spain) have clearly led the way in detection of inorganic/organometallic molecules in space, computational support and even rational design can provide novel avenues for the detection of molecules containing atoms not typically studied in most laboratories. The application of quantum chemistry to other elements beyond carbon and its cronies at the top right of the periodic table promises a better understanding of the observable universe. It will also provide novel and fundamental chemical insights pushing the "central science" into new molecular territory.
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Affiliation(s)
- Ryan C. Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Nathan J. DeYonker
- Department of Chemistry, University of Memphis, Memphis, Tennessee 38152, United States
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20
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Dereka B, Yu Q, Lewis NHC, Carpenter WB, Bowman JM, Tokmakoff A. Crossover from hydrogen to chemical bonding. Science 2021; 371:160-164. [DOI: 10.1126/science.abe1951] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/20/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Bogdan Dereka
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Qi Yu
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322, USA
| | - Nicholas H. C. Lewis
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | - William B. Carpenter
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Joel M. Bowman
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322, USA
| | - Andrei Tokmakoff
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
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21
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Dallas J, Flint A, Fortenberry RC. Solvation of HeH+ in neon atoms: Proton-bound complexes of mixed He and Ne. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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22
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Fortenberry RC, Trabelsi T, Francisco JS. Anharmonic Frequencies and Spectroscopic Constants of OAlOH and AlOH: Strong Bonding but Unhindered Motion. J Phys Chem A 2020; 124:8834-8841. [PMID: 33044814 DOI: 10.1021/acs.jpca.0c07945] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The astrophysical buildup of premineral nanocrystals from atoms to the smallest network-covalent solids will require observations of various small molecules containing the most common elements in minerals including aluminum and oxygen. The present work utilizes high-level quantum chemical quartic force field (QFF) approaches to produce anharmonic vibrational frequencies and spectroscopic constants for such species. The computed Beff for the astrochemically known AlOH molecule at 15780.5 MHz is a mere 40 MHz above the experimental value implying that the Beff for OAlOH at 5580.9 MHz is similarly accurate. The additional 7.31 D dipole moment in OAlOH implies that this molecule is a viable target for interstellar observation. Unlike the other anharmonic vibrational frequencies reported in this work, the Al-O-H bending frequencies in both AlOH and OAlOH are poorly described in the present QFF results. However, this failing actually highlights the fact that these bends are exceptionally floppy yet with counterintuitive exceedingly strong bonding. The Al-O bond energies are 128.2 and 107.2 kcal/mol, respective of AlOH and OAlOH, while the barriers to linearity are meager 16.6 and 380.7 cm-1 (0.1 and 1.1 kcal/mol).
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Tarek Trabelsi
- Department of Earth and Environmental Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joseph S Francisco
- Department of Earth and Environmental Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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23
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McDonald DC, Rittgers BM, Theis RA, Fortenberry RC, Marks JH, Leicht D, Duncan MA. Infrared spectroscopy and anharmonic theory of H 3 +Ar 2,3 complexes: The role of symmetry in solvation. J Chem Phys 2020; 153:134305. [PMID: 33032436 DOI: 10.1063/5.0023205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The vibrational spectra of H3 +Ar2,3 and D3 +Ar2,3 are investigated in the 2000 cm-1 to 4500 cm-1 region through a combination of mass-selected infrared laser photodissociation spectroscopy and computational work including the effects of anharmonicity. In the reduced symmetry of the di-argon complex, vibrational activity is detected in the regions of both the symmetric and antisymmetric hydrogen stretching modes of H3 +. The tri-argon complex restores the D3h symmetry of the H3 + ion, with a concomitant reduction in the vibrational activity that is limited to the region of the antisymmetric stretch. Throughout these spectra, additional bands are detected beyond those predicted with harmonic vibrational theory. Anharmonic theory is able to reproduce some of the additional bands, with varying degrees of success.
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Affiliation(s)
- D C McDonald
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - B M Rittgers
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - R A Theis
- Department of Chemistry and Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, USA
| | - R C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, USA
| | - J H Marks
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - D Leicht
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - M A Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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24
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Boutwell D, Okere O, Omodemi O, Toledo A, Barrios A, Olocha M, Kaledin M. Analysis of the Proton Transfer Bands in the Infrared Spectra of Linear N 2H +···OC and N 2D +···OC Complexes Using Electric Field-Driven Classical Trajectories. J Phys Chem A 2020; 124:7549-7558. [PMID: 32808782 DOI: 10.1021/acs.jpca.0c06756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we describe ab initio calculations and assignment of infrared (IR) spectra of hydrogen-bonded ion-molecular complexes that involve a fluxional proton: the linear N2H+···OC and N2D+···OC complexes. Given the challenges of describing fluxional proton dynamics and especially its IR activity, we use electric field-driven classical trajectories, i.e., the driven molecular dynamics (DMD) method that was developed by us in recent years and for similar applications, in conjunction with high-level electronic structure theory. Namely, we present a modified and a numerically efficient implementation of DMD specifically for direct (or "on the fly") calculations, which we carry out at the MP2-F12/AVDZ level of theory for the potential energy surface (PES) and MP2/AVDZ for the dipole moment surfaces (DMSs). Detailed analysis of the PES, DMS, and the time-dependence of the first derivative of the DMS, referred to as the driving force, for the highly fluxional vibrations involving H+/D+ revealed that the strongly non-harmonic PES and non-linear DMS yield remarkably complex vibrational spectra. Interestingly, the classical trajectories reveal a doublet in the proton transfer part of the spectrum with the two peaks at 1800 and 1980 cm-1. We find that their shared intensity is due to a Fermi-like resonance interaction, within the classical limit, of the H+ parallel stretch fundamental and an H+ perpendicular bending overtone. This doublet is also observed in the deuterated species at 1360 and 1460 cm-1.
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Affiliation(s)
- Dalton Boutwell
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
| | - Onyinye Okere
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
| | - Oluwaseun Omodemi
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
| | - Alexander Toledo
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
| | - Antonio Barrios
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
| | - Monique Olocha
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
| | - Martina Kaledin
- Department of Chemistry & Biochemistry, Kennesaw State University, 370 Paulding Ave NW, Box # 1203, Kennesaw, Georgia 30144, United States
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25
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Abstract
The structure and vibrational spectra of protonated Ar clusters ArnH+ (n = 2-3) are studied using potential energy surfaces at the CCSD(T)/aug-cc-pVTZ level and basis set. Ar binding energies, as well as position isomerism in Ar3H+, were investigated. In our previous work, the spectra of Ar2H+ reveal a strong progression of combination bands, which involves the asymmetric Ar-H+ stretch with multiple quanta of the symmetric Ar-H+ stretch. In this work, insights on the origin of such progression were examined using an adiabatic model. In addition, contributions from mechanical and electrical anharmonicity on the progressions' intensities were also examined. Comparison of the calculated spectrum for the bare and Ar-tagged ions reveals that the reduction of the symmetry group, from D∞h to either C∞v or C2v, results in a richer vibrational structure in the 500-1700 cm-1 region. When compared with previously reported action spectra (D. C. McDonald III, D. T. Mauney, D. Leicht, J. H. Marks, J. A. Tan, J.-L. Kuo, and M. A. Duncan, J. Chem. Phys., 2016, 145, 231,101), it appears that the position isomers, because of the binding of the weakly bound Ar messenger, are needed to account for the additional bands in the infrared photodissociation spectrum for Ar3H+. These findings demonstrate the active role of the messenger atom in relaxing some of the selection rules for the bare ion's vibrational transitions - resulting in an augmentation of the bands in the action spectrum.
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Affiliation(s)
- Jake A Tan
- Institute of Atomic and Molecular Sciences, Academia Sinica, No.1 Roosevelt Road, Section 4, Da-an District, Taipei City 10617, Taiwan (ROC)
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica, No.1 Roosevelt Road, Section 4, Da-an District, Taipei City 10617, Taiwan (ROC)
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26
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Leicht D, Rittgers BM, Douberly GE, Wagner JP, McDonald DC, Mauney DT, Tsuge M, Lee YP, Duncan MA. Infrared spectroscopy of H+(CO)2 in the gas phase and in para-hydrogen matrices. J Chem Phys 2020; 153:084305. [DOI: 10.1063/5.0019731] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel Leicht
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | | | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - J. Philipp Wagner
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - David C. McDonald
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Daniel T. Mauney
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Masashi Tsuge
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Yuan-Pern Lee
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
- Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu 30010, Taiwan
- Institute of Atomic and Molecular Sciences Academia Sinica, Taipei 10617, Taiwan
| | - Michael A. Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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27
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Westbrook BR, Del Rio WA, Lee TJ, Fortenberry RC. Overcoming the out-of-plane bending issue in an aromatic hydrocarbon: the anharmonic vibrational frequencies of c-(CH)C 3H 2. Phys Chem Chem Phys 2020; 22:12951-12958. [PMID: 32478782 DOI: 10.1039/d0cp01889a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The challenges associated with the out-of-plane bending problem in multiply-bonded hydrocarbon molecules can be mitigated in quartic force field analyses by varying the step size in the out-of-plane coordinates. Carbon is a highly prevalent element in astronomical and terrestrial environments, but this major piece of its spectra has eluded theoretical examinations for decades. Earlier explanations for this problem focused on method and basis set issues, while this work seeks to corroborate the recent diagnosis as a numerical instability problem related to the generation of the potential energy surface. Explicit anharmonic frequencies for c-(CH)C3H2+ are computed using a quartic force field and the CCSD(T)-F12b method with cc-pVDZ-F12, cc-pVTZ-F12, and aug-cc-pVTZ basis sets. The first of these is shown to offer accuracy comparable to that of the latter two with a substantial reduction in computational time. Additionally, c-(CH)C3H2+ is shown to have two fundamental frequencies at the onset of the interstellar unidentified infrared bands, at 5.134 and 6.088 μm or 1947.9 and 1642.6 cm-1, respectively. This suggests that the results in the present study should assist in the attribution of parts of these aromatic bands, as well as provide data in support of the laboratory or astronomical detection of c-(CH)C3H2+.
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Affiliation(s)
- Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, MS 38677-1848, USA.
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28
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Westbrook BR, Fortenberry RC. Anharmonic Frequencies of (MO) 2 and Related Hydrides for M = Mg, Al, Si, P, S, Ca, and Ti and Heuristics for Predicting Anharmonic Corrections of Inorganic Oxides. J Phys Chem A 2020; 124:3191-3204. [PMID: 32212705 DOI: 10.1021/acs.jpca.0c01609] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The low-frequency vibrational fundamentals of D2h inorganic oxides are readily modeled by heuristic scaling factors at fractions of the computational cost compared to explicit anharmonic frequency computations. Oxygen and the other elements in the present study are abundant in geochemical environments and have the potential to aggregate into minerals in planet-forming regions or in the remnants of supernovae. Explicit quartic force field computations at the CCSD(T)-F12b/cc-pVTZ-F12 level of theory generate scaling factors that accurately predict the anharmonic frequencies with an average error of less than 1.0 cm-1 for both the metal-oxygen stretching frequencies and the torsion and antisymmetric stretching frequencies. Inclusion of hydrogen motions is less absolutely accurate but is similarly relatively predictive. The fundamental vibrational frequencies for the seven tetra-atomic inorganic oxides examined presently fall below 876 cm-1 and most of the hydrogenated species do as well. Additionally, ν6 for the SiO dimer is shown to have an intensity of 562 km mol-1, with each of the other molecules having one or more frequencies with intensities greater than 80 km mol-1, again with most in the low-frequency infrared range. These intensities and the frequencies computed in the present study should assist in laboratory characterization and potential interstellar or circumstellar observation.
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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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29
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Rovibrational Spectral Analysis of CO3 and C2O3: Potential Sources for O2 Observed in Comet 67P/Churyumov–Gerasimenko. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/2041-8213/ab53e8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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30
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Hooper R, Boutwell D, Kaledin M. Assignment of Infrared-Active Combination Bands in the Vibrational Spectra of Protonated Molecular Clusters Using Driven Classical Trajectories: Application to N 4H + and N 4D . J Phys Chem A 2019; 123:5613-5620. [PMID: 31244119 DOI: 10.1021/acs.jpca.9b04480] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the utility of the driven molecular dynamics (DMD) approach to complex molecular vibrations by applying it to linear clusters with several degenerate vibrational modes and infrared (IR) intense combination bands. Here, the prominent features in N4H+ and N4D+ IR spectra, reported and described by others previously, have been characterized for the first time by DMD using recently published high-level potential and dipole moment surfaces. Namely, the calculations closely correlate the parallel proton stretch vibration in N4H+, at 750 cm-1, with the one observed experimentally at 743 cm-1. Second, the intense IR-active combination bands found in experimental spectra within 900-1100 cm-1 have been properly recovered by DMD at 950 cm-1 as strongly IR-active and confirmed as consisting of H+ asymmetric stretch and N2···N2 intermolecular symmetric stretch modes. Furthermore, we show that certain combination bands involving overtone transitions may be recovered by DMD using a hard-driving regime, such as the 1409 cm-1 band measured in N4H+, revealed by DMD at 1375 cm-1, and assigned to a progressive combination of the parallel H+ stretch and two quanta of N2···N2 stretch, in agreement with quantum mechanical studies reported previously by others.
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Affiliation(s)
- Reagan Hooper
- Department of Chemistry & Biochemistry , Kennesaw State University , 370 Paulding Avenue NW , Box # 1203, Kennesaw , Georgia 30144 , Unites States
| | - Dalton Boutwell
- Department of Chemistry & Biochemistry , Kennesaw State University , 370 Paulding Avenue NW , Box # 1203, Kennesaw , Georgia 30144 , Unites States
| | - Martina Kaledin
- Department of Chemistry & Biochemistry , Kennesaw State University , 370 Paulding Avenue NW , Box # 1203, Kennesaw , Georgia 30144 , Unites States
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31
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Puzzarini C, Bloino J, Tasinato N, Barone V. Accuracy and Interpretability: The Devil and the Holy Grail. New Routes across Old Boundaries in Computational Spectroscopy. Chem Rev 2019; 119:8131-8191. [DOI: 10.1021/acs.chemrev.9b00007] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Cristina Puzzarini
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | - Julien Bloino
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Nicola Tasinato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
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32
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Tan JA, Kuo JL. A theoretical study on the infrared signatures of proton-bound rare gas dimers (Rg-H +-Rg), Rg = {Ne, Ar, Kr, and Xe}. J Chem Phys 2019; 150:124305. [PMID: 30927880 DOI: 10.1063/1.5090031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The infrared spectrum of proton-bound rare gas dimers has been extensively studied via matrix isolation spectroscopy. However, little attention has been paid on their spectrum in the gas phase. Most of the Rg2H+ has not been detected outside the matrix environment. Recently, ArnH+ (n = 3-7) has been first detected in the gas-phase [D. C. McDonald et al., J. Chem. Phys. 145, 231101 (2016)]. In that work, anharmonic theory can reproduce the observed vibrational structure. In this paper, we extend the existing theory to examine the vibrational signatures of Rg2H+, Rg = {Ne, Ar, Kr, and Xe}. The successive binding of Rg to H+ was investigated through the calculation of stepwise formation energies. It was found that this binding is anti-cooperative. High-level full-dimensional potential energy surfaces at the CCSD(T)/aug-cc-pVQZ//MP2/aug-cc-pVQZ were constructed and used in the anharmonic calculation via discrete variable representation. We found that the potential coupling between the symmetric and asymmetric Rg-H+ stretch (ν1 and ν3 respectively) causes a series of bright n1ν1 + ν3 progressions. From Ne2H+ to Xe2H+, an enhancement of intensities for these bands was observed.
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Affiliation(s)
- Jake A Tan
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
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33
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Thomas DA, Mucha E, Lettow M, Meijer G, Rossi M, von Helden G. Characterization of a trans-trans Carbonic Acid-Fluoride Complex by Infrared Action Spectroscopy in Helium Nanodroplets. J Am Chem Soc 2019; 141:5815-5823. [PMID: 30883095 PMCID: PMC6727381 DOI: 10.1021/jacs.8b13542] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
![]()
The high Lewis basicity
and small ionic radius of fluoride promote
the formation of strong ionic hydrogen bonds in the complexation of
fluoride with protic molecules. Herein, we report that carbonic acid,
a thermodynamically disfavored species that is challenging to investigate
experimentally, forms a complex with fluoride in the gas phase. Intriguingly,
this complex is highly stable and is observed in abundance upon nanoelectrospray
ionization of an aqueous sodium fluoride solution in the presence
of gas-phase carbon dioxide. We characterize the structure and properties
of the carbonic acid–fluoride complex, F–(H2CO3), and its deuterated isotopologue, F–(D2CO3), by helium nanodroplet
infrared action spectroscopy in the photon energy range of 390–2800
cm–1. The complex adopts a C2v symmetry structure with the carbonic acid
in a planar trans–trans conformation and both OH groups forming
ionic hydrogen bonds with the fluoride. Substantial vibrational anharmonic
effects are observed in the infrared spectra, most notably a strong
blue shift of the symmetric hydrogen stretching fundamental relative
to predictions from the harmonic approximation or vibrational second-order
perturbation theory. Ab initio thermostated ring-polymer molecular
dynamics simulations indicate that this blue shift originates from
strong coupling between the hydrogen stretching and bending vibrations,
resulting in an effective weakening of the OH···F– ionic hydrogen bonds.
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Affiliation(s)
- Daniel A Thomas
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Eike Mucha
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Maike Lettow
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Mariana Rossi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Gert von Helden
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
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34
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A Small Molecule with PAH Vibrational Properties and a Detectable Rotational Spectrum: c-(C)C3H2, Cyclopropenylidenyl Carbene. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-4357/aaf85a] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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35
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Fortenberry RC, Lee TJ. Computational vibrational spectroscopy for the detection of molecules in space. ANNUAL REPORTS IN COMPUTATIONAL CHEMISTRY 2019. [DOI: 10.1016/bs.arcc.2019.08.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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36
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Qu C, Bowman JM. Quantum approaches to vibrational dynamics and spectroscopy: is ease of interpretation sacrificed as rigor increases? Phys Chem Chem Phys 2019; 21:3397-3413. [DOI: 10.1039/c8cp04990d] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The subject of this Perspective is quantum approaches, beyond the harmonic approximation, to vibrational dynamics and IR spectroscopy.
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Affiliation(s)
- Chen Qu
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University
- Atlanta
- USA
| | - Joel M. Bowman
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University
- Atlanta
- USA
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37
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Fortenberry RC, Ascenzi D. ArCH 2 + : A Detectable Noble Gas Molecule. Chemphyschem 2018; 19:3388-3392. [PMID: 30370986 DOI: 10.1002/cphc.201800888] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/23/2018] [Indexed: 11/07/2022]
Abstract
The noble gas molecular cation, ArCH2 + , has been observed in mass spectrometry experiments, and the present work is providing high-level quantum chemical predictions for the vibrational and rotational spectroscopic data necessary to observe this molecule in situ in other laboratory conditions. The Ar-C stretch in this cation is a bright fundamental vibrational frequency that should be observable in the early regions of the far-infrared at 421.2 cm-1 for the universally most common 36 Ar isotope. The near-prolate nature of this molecule and its 2.91 D dipole moment should also make it distinguishable for submillimeter detection, as well. Furthermore, the Ar-C bond strength in ArCH2 + is greater than the global minimum for the dissociation of the experimentally known ArOH+ cation. As a result, the infrared spectrum of this simple organo-noble gas molecule is likely waiting to be observed and may already exist in the spectra of hydrocarbon cations in argon-matrix condensed phase experiments.
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Affiliation(s)
- Ryan C Fortenberry
- University of Mississippi, Department of Chemistry & Biochemistry, University, MS 38677-1848, U.S.A
| | - Daniela Ascenzi
- University of Trento, Department of Physics, Via Sommarive 14, 38050, Povo Trento, Italy
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38
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Tan JA, Kuo JL. Multilevel Approach for Direct VSCF/VCI MULTIMODE Calculations with Applications to Large “Zundel” Cations. J Chem Theory Comput 2018; 14:6405-6416. [DOI: 10.1021/acs.jctc.8b00679] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jake A. Tan
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan (ROC)
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan (ROC)
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39
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Palmer CZ, Fortenberry RC. Rovibrational Considerations for the Monomers and Dimers of Magnesium Hydride and Magnesium Fluoride. J Phys Chem A 2018; 122:7079-7088. [DOI: 10.1021/acs.jpca.8b06611] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. Zachary Palmer
- Department of Chemistry & Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, United States
| | - Ryan C. Fortenberry
- Department of Chemistry & Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, United States
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677, United States
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40
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Fortenberry RC, Novak CM, Lee TJ. Rovibrational analysis of c-SiC 2H 2: Further evidence for out-of-plane bending issues in correlated methods. J Chem Phys 2018; 149:024303. [PMID: 30007394 DOI: 10.1063/1.5043166] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While the issue of properly describing the out-of-plane bends (OPBs) in sp2 hybridized carbon atoms has reappeared for c-SiC2H2, the present quantum chemical study provides a new characterization of this molecule in order to aid in its potential detection in astrophysically relevant studies. Combining the previous, high-level approach with MP2-F12/aug-cc-pVDZ gives exceptionally accurate results for the comparison of experimental rotational constants and seemingly reliable vibrational frequencies. Most notably, the brightest fundamental vibrational frequency in c-SiC2H2, the b1 OPB, is predicted to lie at 673.4 cm-1, within 4.0 cm-1 of the previous matrix isolation experiment. As with c-C3H2, CCSD(T)-F12/aug-cc-pVTZ appears to be quite susceptible to over estimating the OPB anharmonic correction in c-SiC2H2 and may also do such for in-plane bends, as well. MP2-F12/aug-cc-pVDZ is less susceptible to these errors, and increasing the step size reduces this positive anharmonicity issue in both the cases. The OPB underestimation, however, likely still remains. Finally, estimates for some anharmonic vibrational frequencies are provided for the methylated form, c-SiC2HCH3, which is likely also a product of gas phase reactions of ·SiH with various alkynes.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Oxford, Mississippi 38677, USA
| | - Carlie M Novak
- Department of Chemistry and Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, USA
| | - Timothy J Lee
- NASA Ames Research Center, MS 245-3 Moffett Field, California 94035 USA
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41
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Affiliation(s)
- Chen Qu
- Department of Chemistry, Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Qi Yu
- Department of Chemistry, Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Joel M. Bowman
- Department of Chemistry, Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
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42
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Kraus P, Obenchain DA, Frank I. Benchmark-Quality Semiexperimental Structural Parameters of van der Waals Complexes. J Phys Chem A 2018; 122:1077-1087. [PMID: 29301068 DOI: 10.1021/acs.jpca.7b10797] [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
Accurate data sets including noncovalent interactions have become essential for benchmarking computational methods. However, while there is much focus on obtaining an accurate description of relative energies, reliable prediction of accurate equilibrium geometries is also important. To facilitate the benchmarking of computed geometries, the current work includes an accurate data set of semiexperimental equilibrium geometries of noncovalent complexes that can be directly compared to ab initio data. The structures are based on high-accuracy spectroscopic data, combined with vibrational corrections at the double-hybrid density functional level. The current work is designed to complement available data sets of semiexperimental geometries of small rigid molecules and ab initio geometries of complexes. The benchmark-quality data comprises 16 complexes and includes dispersion interactions, hydrogen bonding, CH/π···π interactions, and trimers. In addition to the reference data, accurate counterpoise-corrected geometries have been obtained up to the CCSD level, along with interaction energies. A short overview of the performance of computational methods, including dispersion-corrected B3LYP and B2PLYP functionals, is also included.
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Affiliation(s)
- P Kraus
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover , Callinstraße 3A, 30167 Hannover, Germany
| | - D A Obenchain
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover , Callinstraße 3A, 30167 Hannover, Germany
| | - I Frank
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover , Callinstraße 3A, 30167 Hannover, Germany
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43
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Tsuge M, Tseng CY, Lee YP. Spectroscopy of prospective interstellar ions and radicals isolated in para-hydrogen matrices. Phys Chem Chem Phys 2018; 20:5344-5358. [DOI: 10.1039/c7cp05680j] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The p-H2 matrix-isolation technique coupled with photolysis in situ or electron bombardment produces protonated or hydrogenated species important in astrochemistry.
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Affiliation(s)
- Masashi Tsuge
- Department of Applied Chemistry and Institute of Molecular Science
- National Chiao Tung University
- Hsinchu 30010
- Taiwan
| | - Chih-Yu Tseng
- Department of Applied Chemistry and Institute of Molecular Science
- National Chiao Tung University
- Hsinchu 30010
- Taiwan
| | - Yuan-Pern Lee
- Department of Applied Chemistry and Institute of Molecular Science
- National Chiao Tung University
- Hsinchu 30010
- Taiwan
- Institute of Atomic and Molecular Sciences
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44
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Biczysko M, Bloino J, Puzzarini C. Computational challenges in Astrochemistry. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1349] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Malgorzata Biczysko
- International Center for Quantum and Molecular Structures, College of SciencesShanghai University Shanghai China
| | - Julien Bloino
- Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti OrganoMetalliciUOS di Pisa, Area della Ricerca CNR Pisa Italy
- Scuola Normale Superiore Classe di Scienze, Pisa Italy
| | - Cristina Puzzarini
- Department of Chemistry “Giacomo Ciamician”University of Bologna Bologna Italy
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45
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Fortenberry RC, Francisco JS, Lee TJ. Quantum Chemical Rovibrational Analysis of the HOSO Radical. J Phys Chem A 2017; 121:8108-8114. [DOI: 10.1021/acs.jpca.7b08121] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryan C. Fortenberry
- Department of Chemistry & Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, United States
| | - Joseph S. Francisco
- Department
of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Timothy J. Lee
- NASA Ames Research Center, MS 245-3 Moffett Field, California 94035-1000, United States
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46
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Fortenberry RC, Lee TJ, Huang X. Towards completing the cyclopropenylidene cycle: rovibrational analysis of cyclic N 3+, CNN, HCNN +, and CNC . Phys Chem Chem Phys 2017; 19:22860-22869. [PMID: 28812071 DOI: 10.1039/c7cp04257d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The simple aromatic hydrocarbon, cyclopropenylidene (c-C3H2), is a known, naturally-occurring molecule. The question remains as to whether its isoelectronic, cyclic, fellow aromatics of c-N3+, c-CNN, HCNN+, and c-CNC- are as well. Each of these are exciting objects for observation of Titan, and the rotational constants and vibrational frequencies produced here will allow for remote sensing of Titan's atmosphere or other astrophysical or terrestrial sources. None of these four aromatic species are vibrationally strong absorbers/emitters, but the two ions, HCNN+ and c-CNC-, have dipole moments of greater than 3 D and 1 D, respectively, making them good targets for rotational spectroscopic observation. Each of these molecules is shown here to exhibit its own, unique vibrational properties, but the general trends put the vibrational behavior for corresponding fundamental modes within close ranges of one another, even producing nearly the same heavy atom, symmetric stretching frequencies for HCNN+ and c-C3H2 at 1600 cm-1. The c-N3+ cation is confirmed to be fairly unstable and has almost no intensity in its ν2 fundamental. Hence, it will likely remain difficult to characterize experimentally.
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Affiliation(s)
- Ryan C Fortenberry
- Georgia Southern University, Department of Chemistry and Biochemistry, Statesboro, GA 30460, USA.
| | - Timothy J Lee
- MS 245-3, NASA Ames Research Center, Moffett Field, CA 94035-1000, USA
| | - Xinchuan Huang
- SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043, USA
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47
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Fortenberry RC, Thackston R, Francisco JS, Lee TJ. Toward the laboratory identification of the not-so-simple NS2neutral and anion isomers. J Chem Phys 2017; 147:074303. [DOI: 10.1063/1.4985901] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ryan C. Fortenberry
- Department of Chemistry and Biochemistry, Georgia Southern University, Statesboro, Georgia 30460-8064, USA
| | - Russell Thackston
- Department of Information Technology, Georgia Southern University, Statesboro, Georgia 30460-8150, USA
| | - Joseph S. Francisco
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
| | - Timothy J. Lee
- MS 245-1, NASA Ames Research Center, Moffett Field, California 94035-1000, USA
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48
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Bassett MK, Fortenberry RC. Symmetry breaking and spectral considerations of the surprisingly floppy c-C 3H radical and the related dipole-bound excited state of c-C 3H . J Chem Phys 2017; 146:224303. [PMID: 29166048 DOI: 10.1063/1.4985095] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The C3H radical is believed to be prevalent throughout the interstellar medium and may be involved in the formation of polycyclic aromatic hydrocarbons. C3H exists as both a linear and a cyclic isomer. The C2v cyclopropenylidenyl radical isomer was detected in the dark molecular cloud TMC-1, and the linear propenylidenyl radical isomer has been observed in various dark molecular clouds. Even though the c-C3H radical has been classified rotationally, the vibrational frequencies of this seemingly important interstellar molecule have never been directly observed. Established, highly accurate quartic force field methodologies are employed here to compute useful geometrical data, spectroscopic constants, and vibrational frequencies. The computed rotational constants are consistent with the experimental results. Consequently, the three a1 (ν1, ν2, and ν3) and one b1 (ν6) anharmonic vibrational frequencies at 3117.7 cm-1, 1564.3 cm-1, 1198.5 cm-1, and 826.7 cm-1, respectively, are reliable predictions for these, as of yet unseen, observables. Unfortunately, the two b2 fundamentals (ν4 and ν5) cannot be treated adequately in the current approach due to a flat and possible double-well potential described in detail herein. The dipole-bound excited state of the anion suffers from the same issues and may not even be bound. However, the trusted fundamental vibrational frequencies described for the neutral radical should not be affected by this deformity and are the first robustly produced for c-C3H. The insights gained here will also be applicable to other structures containing three-membered bare and exposed carbon rings that are surprisingly floppy in nature.
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Affiliation(s)
- Matthew K Bassett
- Department of Chemistry and Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, USA
| | - Ryan C Fortenberry
- Department of Chemistry and Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, USA
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49
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Fortenberry RC. The rovibrational nature of cis- and trans-HNNS: A possible nitrogen molecule progenitor. J Chem Phys 2017; 145:204302. [PMID: 27908132 DOI: 10.1063/1.4968036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The HNNS radical has been promoted recently as a viable intermediate in the interstellar creation of the spectroscopically elusive nitrogen molecule. Any confirmation of this pathway or utilizing HNNS as a tracer of N2 depends upon the ability to observe the radical intermediate whether in the laboratory or in the interstellar medium. Established and accurate quantum chemical procedures are employed here to produce spectroscopic constants, fundamental vibrational frequencies, and intensities that can be utilized for any possible detection of HNNS. While trans-HNNS is confirmed here to be 3.0 kcal/mol lower in energy than cis-HNNS, the latter will be more readily observed rotationally due to its significantly larger dipole moment. The N-N bond in cis-HNNS is stronger than in trans-HNNS, and earlier work has suggested that cis-HNNS is more useful in the creation of N2 from NH and NS. Hence, the detection of cis-HNNS may be of greater value anyway. Furthermore, the N-N stretch in either conformer is also exceptionally bright and will occur in the mid-infrared with nearly 30 cm-1 separating the fundamentals of the two conformers. Finally, the low isomerization barrier can be affected significantly upon deuteration also making ND an interesting consideration as a starting material in the interstellar formation of N2.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry and Biochemistry, Georgia Southern University, Statesboro, Georgia 30460, USA
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50
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On the Detectability of the ${\tilde{{\boldsymbol{X}}}}^{2}{\boldsymbol{A}}^{\prime\prime} $ HSS, HSO, and HOS Radicals in the Interstellar Medium. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-4357/aa582d] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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