1
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Yang EL, Talbot JJ, Spencer RJ, Steele RP. Pitfalls in the n-mode representation of vibrational potentials. J Chem Phys 2023; 159:204104. [PMID: 38010326 DOI: 10.1063/5.0176612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/19/2023] [Indexed: 11/29/2023] Open
Abstract
Simulations of anharmonic vibrational motion rely on computationally expedient representations of the governing potential energy surface. The n-mode representation (n-MR)-effectively a many-body expansion in the space of molecular vibrations-is a general and efficient approach that is often used for this purpose in vibrational self-consistent field (VSCF) calculations and correlated analogues thereof. In the present analysis, a lack of convergence in many VSCF calculations is shown to originate from negative and unbound potentials at truncated orders of the n-MR expansion. For cases of strong anharmonic coupling between modes, the n-MR can both dip below the true global minimum of the potential surface and lead to effective single-mode potentials in VSCF that do not correspond to bound vibrational problems, even for bound total potentials. The present analysis serves mainly as a pathology report of this issue. Furthermore, this insight into the origin of VSCF non-convergence provides a simple, albeit ad hoc, route to correct the problem by "painting in" the full representation of groups of modes that exhibit these negative potentials at little additional computational cost. Somewhat surprisingly, this approach also reasonably approximates the results of the next-higher n-MR order and identifies groups of modes with particularly strong coupling. The method is shown to identify and correct problematic triples of modes-and restore SCF convergence-in two-mode representations of challenging test systems, including the water dimer and trimer, as well as protonated tropine.
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Affiliation(s)
- Emily L Yang
- Department of Chemistry, The University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, USA
- Henry Eyring Center for Theoretical Chemistry, The University of Utah, Salt Lake City, Utah 84112, USA
| | - Justin J Talbot
- Department of Chemistry, University of California-Berkeley, 420 Latimer Hall, Berkeley, California 94720, USA
| | - Ryan J Spencer
- Department of Chemistry, The University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, USA
- Henry Eyring Center for Theoretical Chemistry, The University of Utah, Salt Lake City, Utah 84112, USA
| | - Ryan P Steele
- Department of Chemistry, The University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, USA
- Henry Eyring Center for Theoretical Chemistry, The University of Utah, Salt Lake City, Utah 84112, USA
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2
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Zhanserkeev AA, Yang EL, Steele RP. Accelerating Anharmonic Spectroscopy Simulations via Local-Mode, Multilevel Methods. J Chem Theory Comput 2023; 19:5572-5585. [PMID: 37555634 DOI: 10.1021/acs.jctc.3c00589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Ab initio computer simulations of anharmonic vibrational spectra provide nuanced insight into the vibrational behavior of molecules and complexes. The computational bottleneck in such simulations, particularly for ab initio potentials, is often the generation of mode-coupling potentials. Focusing specifically on two-mode couplings in this analysis, the combination of a local-mode representation and multilevel methods is demonstrated to be particularly symbiotic. In this approach, a low-level quantum chemistry method is employed to predict the pairwise couplings that should be included at the target level of theory in vibrational self-consistent field (and similar) calculations. Pairs that are excluded by this approach are "recycled" at the low level of theory. Furthermore, because this low-level pre-screening will eventually become the computational bottleneck for sufficiently large chemical systems, distance-based truncation is applied to these low-level predictions without substantive loss of accuracy. This combination is demonstrated to yield sub-wavenumber fidelity with reference vibrational transitions when including only a small fraction of target-level couplings; the overhead of predicting these couplings, particularly when employing distance-based, local-mode cutoffs, is a trivial added cost. This combined approach is assessed on a series of test cases, including ethylene, hexatriene, and the alanine dipeptide. Vibrational self-consistent field (VSCF) spectra were obtained with an RI-MP2/cc-pVTZ potential for the dipeptide, at approximately a 5-fold reduction in computational cost. Considerable optimism for increased accelerations for larger systems and higher-order couplings is also justified, based on this investigation.
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Affiliation(s)
- Asylbek A Zhanserkeev
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Emily L Yang
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Ryan P Steele
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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3
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Hanson-Heine MWD. Static Electron Correlation in Anharmonic Molecular Vibrations: A Hybrid TAO-DFT Study. J Phys Chem A 2022; 126:7273-7282. [PMID: 36164938 PMCID: PMC9574917 DOI: 10.1021/acs.jpca.2c05881] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Hybrid thermally-assisted-occupation density functional theory is used to examine the effects of static electron correlation on the prediction of a benchmark set of experimentally observed molecular vibrational frequencies. The B3LYP and B97-1 thermally-assisted-occupation measure of static electron correlation is important for describing the vibrations of many of the molecules that make up several popular test sets of experimental data. Shifts are seen for known multireference systems and for many molecules containing atoms from the second row of the periodic table of elements. Several molecules only show significant shifts in select vibrational modes, and significant improvements are seen for the prediction of hydrogen stretching frequencies throughout the test set.
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4
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Hanson-Heine MWD. Reduced Two-Electron Interactions in Anharmonic Molecular Vibrational Calculations Involving Localized Normal Coordinates. J Chem Theory Comput 2021; 17:4383-4391. [PMID: 34087068 DOI: 10.1021/acs.jctc.1c00314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spatially localized vibrational normal mode coordinates are shown to reduce the importance of calculating the full set of two-electron terms in the molecular electronic Schrödinger equation. Electron correlation and dispersion interactions become less significant in (E,E)-1,3,5,7-octatetraene vibrational self-consistent field calculations when displacing remote atoms along multiple coordinates. Electron correlation interactions between spatially remote modes are also found to be less important compared to their corresponding uncorrelated interaction terms. Attenuation of the Coulomb operator indicates that the two-electron terms between remote electrons become less important for accurately describing the strongly contributing mode-coupling terms between sets of localized vibrational modes.
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Mathea T, Petrenko T, Rauhut G. VCI Calculations Based on Canonical and Localized Normal Coordinates for Non-Abelian Molecules: Accurate Assignment of the Vibrational Overtones of Allene. J Phys Chem A 2021; 125:990-998. [DOI: 10.1021/acs.jpca.0c10429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tina Mathea
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Taras Petrenko
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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6
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Baiz CR, Błasiak B, Bredenbeck J, Cho M, Choi JH, Corcelli SA, Dijkstra AG, Feng CJ, Garrett-Roe S, Ge NH, Hanson-Heine MWD, Hirst JD, Jansen TLC, Kwac K, Kubarych KJ, Londergan CH, Maekawa H, Reppert M, Saito S, Roy S, Skinner JL, Stock G, Straub JE, Thielges MC, Tominaga K, Tokmakoff A, Torii H, Wang L, Webb LJ, Zanni MT. Vibrational Spectroscopic Map, Vibrational Spectroscopy, and Intermolecular Interaction. Chem Rev 2020; 120:7152-7218. [PMID: 32598850 PMCID: PMC7710120 DOI: 10.1021/acs.chemrev.9b00813] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Vibrational spectroscopy is an essential tool in chemical analyses, biological assays, and studies of functional materials. Over the past decade, various coherent nonlinear vibrational spectroscopic techniques have been developed and enabled researchers to study time-correlations of the fluctuating frequencies that are directly related to solute-solvent dynamics, dynamical changes in molecular conformations and local electrostatic environments, chemical and biochemical reactions, protein structural dynamics and functions, characteristic processes of functional materials, and so on. In order to gain incisive and quantitative information on the local electrostatic environment, molecular conformation, protein structure and interprotein contacts, ligand binding kinetics, and electric and optical properties of functional materials, a variety of vibrational probes have been developed and site-specifically incorporated into molecular, biological, and material systems for time-resolved vibrational spectroscopic investigation. However, still, an all-encompassing theory that describes the vibrational solvatochromism, electrochromism, and dynamic fluctuation of vibrational frequencies has not been completely established mainly due to the intrinsic complexity of intermolecular interactions in condensed phases. In particular, the amount of data obtained from the linear and nonlinear vibrational spectroscopic experiments has been rapidly increasing, but the lack of a quantitative method to interpret these measurements has been one major obstacle in broadening the applications of these methods. Among various theoretical models, one of the most successful approaches is a semiempirical model generally referred to as the vibrational spectroscopic map that is based on a rigorous theory of intermolecular interactions. Recently, genetic algorithm, neural network, and machine learning approaches have been applied to the development of vibrational solvatochromism theory. In this review, we provide comprehensive descriptions of the theoretical foundation and various examples showing its extraordinary successes in the interpretations of experimental observations. In addition, a brief introduction to a newly created repository Web site (http://frequencymap.org) for vibrational spectroscopic maps is presented. We anticipate that a combination of the vibrational frequency map approach and state-of-the-art multidimensional vibrational spectroscopy will be one of the most fruitful ways to study the structure and dynamics of chemical, biological, and functional molecular systems in the future.
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Affiliation(s)
- Carlos R. Baiz
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, U.S.A
| | - Bartosz Błasiak
- Department of Physical and Quantum Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Jens Bredenbeck
- Johann Wolfgang Goethe-University, Institute of Biophysics, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Jun-Ho Choi
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Steven A. Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, U.S.A
| | - Arend G. Dijkstra
- School of Chemistry and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Chi-Jui Feng
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, U.S.A
| | - Sean Garrett-Roe
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Nien-Hui Ge
- Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025, U.S.A
| | - Magnus W. D. Hanson-Heine
- School of Chemistry, University of Nottingham, Nottingham, University Park, Nottingham, NG7 2RD, U.K
| | - Jonathan D. Hirst
- School of Chemistry, University of Nottingham, Nottingham, University Park, Nottingham, NG7 2RD, U.K
| | - Thomas L. C. Jansen
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Kijeong Kwac
- Center for Molecular Spectroscopy and Dynamics, Seoul 02841, Republic of Korea
| | - Kevin J. Kubarych
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI 48109, U.S.A
| | - Casey H. Londergan
- Department of Chemistry, Haverford College, Haverford, Pennsylvania 19041, U.S.A
| | - Hiroaki Maekawa
- Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025, U.S.A
| | - Mike Reppert
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Shinji Saito
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, 444-8585, Japan
| | - Santanu Roy
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, U.S.A
| | - James L. Skinner
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, U.S.A
| | - Gerhard Stock
- Biomolecular Dynamics, Institute of Physics, Albert Ludwigs University, 79104 Freiburg, Germany
| | - John E. Straub
- Department of Chemistry, Boston University, Boston, MA 02215, U.S.A
| | - Megan C. Thielges
- Department of Chemistry, Indiana University, 800 East Kirkwood, Bloomington, Indiana 47405, U.S.A
| | - Keisuke Tominaga
- Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-0013, Japan
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, U.S.A
| | - Hajime Torii
- Department of Applied Chemistry and Biochemical Engineering, Faculty of Engineering, and Department of Optoelectronics and Nanostructure Science, Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-Ku, Hamamatsu 432-8561, Japan
| | - Lu Wang
- Department of Chemistry and Chemical Biology, Institute for Quantitative Biomedicine, Rutgers University, 174 Frelinghuysen Road, Piscataway, NJ 08854, U.S.A
| | - Lauren J. Webb
- Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street, STOP A5300, Austin, Texas 78712, U.S.A
| | - Martin T. Zanni
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1396, U.S.A
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7
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Mathea T, Rauhut G. Assignment of vibrational states within configuration interaction calculations. J Chem Phys 2020; 152:194112. [DOI: 10.1063/5.0009732] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Tina Mathea
- Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Guntram Rauhut
- Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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8
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Klinting EL, Christiansen O, König C. Toward Accurate Theoretical Vibrational Spectra: A Case Study for Maleimide. J Phys Chem A 2020; 124:2616-2627. [DOI: 10.1021/acs.jpca.9b11915] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
| | - Ove Christiansen
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Carolin König
- Institute of Physical Chemistry, Kiel University, Max-Eyth-Straße 1, D-24118 Kiel, Germany
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9
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Ziegler B, Rauhut G. Localized Normal Coordinates in Accurate Vibrational Structure Calculations: Benchmarks for Small Molecules. J Chem Theory Comput 2019; 15:4187-4196. [DOI: 10.1021/acs.jctc.9b00381] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Benjamin Ziegler
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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10
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Hanson-Heine MWD. Excited-State Vibrational Frequencies: Restricted Virtual Space Time-Dependent Density Functional Theory. J Phys Chem A 2019; 123:2949-2956. [DOI: 10.1021/acs.jpca.8b09642] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Panek PT, Hoeske AA, Jacob CR. On the choice of coordinates in anharmonic theoretical vibrational spectroscopy: Harmonic vs. anharmonic coupling in vibrational configuration interaction. J Chem Phys 2019; 150:054107. [PMID: 30736699 DOI: 10.1063/1.5083186] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
By a suitable choice of coordinates, the computational effort required for calculations of anharmonic vibrational spectra can be reduced significantly. By using suitable localized-mode coordinates obtained from an orthogonal transformation of the conventionally used normal-mode coordinates, anharmonic couplings between modes can be significantly reduced. However, such a transformation introduces harmonic couplings between the localized modes. To elucidate the role of these harmonic couplings, we consider the vibrational self-consistent field (VSCF)/vibrational configuration interaction (VCI) calculations for both few-mode model systems and for ethene as a molecular test case. We show that large harmonic couplings can result in significant errors in localized-mode L-VSCF/L-VCI calculations and study the convergence with respect to the size of the VCI excitation space. To further elucidate the errors introduced by harmonic couplings, we discuss the connection between L-VSCF/L-VCI and vibrational exciton models. With the help of our results, we propose an algorithm for the localization of normal modes in suitable subsets that are chosen to strictly limit the errors introduced by the harmonic couplings while still leading to maximally localized modes.
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Affiliation(s)
- Paweł T Panek
- Technische Universität Braunschweig, Institute of Physical and Theoretical Chemistry, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Adrian A Hoeske
- Technische Universität Braunschweig, Institute of Physical and Theoretical Chemistry, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Christoph R Jacob
- Technische Universität Braunschweig, Institute of Physical and Theoretical Chemistry, Gaußstraße 17, 38106 Braunschweig, Germany
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12
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Hanson-Heine MW, Calladine JA, Yang J, Towrie M, Horvath R, Besley NA, George MW. A combined time-resolved infrared and density functional theory study of the lowest excited states of 9-fluorenone and 2-naphthaldehyde. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.04.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Hanson-Heine MWD. Reduced Basis Set Dependence in Anharmonic Frequency Calculations Involving Localized Coordinates. J Chem Theory Comput 2018; 14:1277-1285. [PMID: 29385338 DOI: 10.1021/acs.jctc.7b01075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Localized normal coordinates are known to be effective in speeding up anharmonic frequency calculations by reducing the complexity of the nuclear Hamiltonian and wave function. Displacing atoms in localized coordinates can also cause relatively small changes in the electronic structure, which can be exploited for further computational efficiency improvements during ab initio electronic structure calculations of the potential energy surface by reducing the electronic basis set dependence. Three different schemes for reducing the basis set dependence have been investigated in this work. These include combining localized coordinate schemes with general mixed basis sets, distance based force-field reductions, and using coordinate specific basis sets. The importance of accurately describing electronic interactions is found to diminish both for multicoordinate terms involving the displacement of remote atoms and when describing the interactions between more remote atoms within specific coordinates.
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14
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Floris SD, Talbot JJ, Wilkinson MJ, Herr JD, Steele RP. Quantum molecular motion in the mixed ion-radical complex, [(H 2O)(H 2S)] . Phys Chem Chem Phys 2016; 18:27450-27459. [PMID: 27711703 DOI: 10.1039/c6cp05299a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The cation dimer of water and hydrogen sulfide, [(H2O)(H2S)]+, serves as a fundamental model for the oxidation chemistry of H2S. The known oxidative metabolism of H2S by biological species in sulfur-rich environments has motivated the study of the inherent properties of this benchmark complex, with possible mechanistic implications for modern water oxidation chemistry. The low-energy isomer of this open-shell ion is a proton-transferred (PT) structure, H3O+SH˙. An alternative PT structure, H3S+OH˙, and a hemibonded (HB) isomer, [H2O·SH2]+, are also stable isomers, placing this complex intermediate to known (H2O)2+ (PT) and (H2S)2+ (HB) limiting regimes. This intermediate character suggested the possibility of unique molecular motion, even in the vibrational ground state. Path integral molecular dynamics and anharmonic vibrational spectroscopy simulations have been performed in this study, in order to understand the inherent quantum molecular motion of this complex. The resulting structural distributions were found to deviate significantly from both classical and harmonic analyses, including the observation of large-amplitude anharmonic motion of the central proton and nearly free rotation of the terminal hydrogens. The predicted vibrational spectra are particularly unique and suggest characteristic signatures of the strong electronic interactions and anharmonic vibrational mode couplings in this radical cation.
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Affiliation(s)
- S D Floris
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, UT, USA.
| | - J J Talbot
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, UT, USA.
| | - M J Wilkinson
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, UT, USA.
| | - J D Herr
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, UT, USA.
| | - R P Steele
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, UT, USA.
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15
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Cheng X, Talbot JJ, Steele RP. Tuning vibrational mode localization with frequency windowing. J Chem Phys 2016; 145:124112. [DOI: 10.1063/1.4963109] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- Xiaolu Cheng
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Justin J. Talbot
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Ryan P. Steele
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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16
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Talbot JJ, Cheng X, Herr JD, Steele RP. Vibrational Signatures of Electronic Properties in Oxidized Water: Unraveling the Anomalous Spectrum of the Water Dimer Cation. J Am Chem Soc 2016; 138:11936-45. [DOI: 10.1021/jacs.6b07182] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Justin J. Talbot
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Xiaolu Cheng
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Jonathan D. Herr
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Ryan P. Steele
- Department
of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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17
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Abstract
Because of the size of polypeptides and proteins, the quantum-chemical prediction of their vibrational spectra presents an exceptionally challenging task. Here, we address one of these challenges, namely, the inclusion of anharmonicities. By performing the expansion of the potential energy surface in localized-mode coordinates instead of the normal-mode coordinates, it becomes possible to calculate anharmonic vibrational spectra of polypeptides efficiently and reliably. We apply this approach to calculate the infrared, Raman, and Raman optical activity spectra of helical alanine polypeptides consisting of up to 20 amino acids. We find that while anharmonicities do not alter the band shapes, simple scaling procedures cannot account for the different shifts found for the individual bands. This closes an important gap in theoretical vibrational spectroscopy by making it possible to quantify the anharmonic contributions and opens the door to a first-principles calculation of multidimensional vibrational spectra.
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Affiliation(s)
- Paweł T Panek
- Institute of Physical and Theoretical Chemistry, TU Braunschweig , Hans-Sommer-Str. 10, 38106 Braunschweig, Germany
| | - Christoph R Jacob
- Institute of Physical and Theoretical Chemistry, TU Braunschweig , Hans-Sommer-Str. 10, 38106 Braunschweig, Germany
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