1
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Schneider M, Rauhut G. VSCF/VCI theory based on the Podolsky Hamiltonian. J Chem Phys 2024; 160:214118. [PMID: 38832735 DOI: 10.1063/5.0213401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 05/14/2024] [Indexed: 06/05/2024] Open
Abstract
While the vibrational spectra of semi-rigid molecules can be computed on approaches relying on the Watson Hamiltonian, floppy molecules or molecular clusters are better described by Hamiltonians, which are capable of dealing with any curvilinear coordinates. It is the kinetic energy operator (KEO) of these Hamiltonians, which render the correlated calculations relying on them rather costly. Novel implementation of vibrational self-consistent field theory and vibrational configuration interaction theory on the basis of the Podolsky Hamiltonian are reported, in which the inverse of the metric tensor, i.e., the G matrix, is represented by an n-mode expansion expressed in terms of polynomials. An analysis of the importance of the individual terms of the KEO with respect to the truncation orders of the n-mode expansion is provided. Benchmark calculations have been performed for the cis-HOPO and methanimine, H2CNH, molecules and are compared to experimental data and to calculations based on the Watson Hamiltonian and the internal coordinate path Hamiltonian.
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Affiliation(s)
- Moritz Schneider
- 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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2
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Rodriguez L, Natalizio M, Sode O. Theoretical Insights into the Vibrational Structure of Carbon Dioxide Rare-Gas Complexes. J Phys Chem A 2024; 128:4199-4205. [PMID: 38770817 DOI: 10.1021/acs.jpca.4c00639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Two new flexible-monomer two-body ab initio potential energy surfaces (PESs) for the neon and krypton van der Waals complexes with carbon dioxide were developed, extending our previous work on the Ar-CO2 molecule. The accuracy of the PESs was validated by their agreement with the vibrational spectrum of the rare-gas complexes. The intermolecular and intramolecular vibrational excitation energies were computed at the vibrational self-consistent field and vibrational configuration interaction levels of theory. Overall, the agreement between theory and experiment is excellent throughout the vibrational spectra. The observed slight splitting of the bending modes, resulting from their nondegeneracy in the complexes, is confirmed by our computations, and the results qualitatively agree with the experiment. The splitting increases with increasing polarizability of the rare-gas atom. Additionally, we explain a discrepancy in the mode assignment in the intermolecular region of the neon complex with our VCI character assignment.
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Affiliation(s)
- Larry Rodriguez
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, United States
| | - Michael Natalizio
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, United States
| | - Olaseni Sode
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, United States
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3
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Bader F, Lauvergnat D, Christiansen O. Efficient vibrationally correlated calculations using n-mode expansion-based kinetic energy operators. Phys Chem Chem Phys 2024; 26:11469-11481. [PMID: 38546727 DOI: 10.1039/d4cp00423j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
Due to its efficiency and flexibility, the n-mode expansion is a frequently used tool for representing molecular potential energy surfaces in quantum chemical simulations. In this work, we investigate the performance of n-mode expansion-based models of kinetic energy operators in general polyspherical coordinate systems. In particular, we assess the operators with respect to accuracy in vibrationally correlated calculations and their effect on potential energy surface construction with the adaptive density guided approach. Our results show that the n-mode expansion-based operator variants are reliable and systematically improvable approximations of the full kinetic energy operator. Moreover, we introduce a workflow to generate the n-mode expanded kinetic energy operators on-the-fly within the adaptive density guided approach. This scheme can be applied in studies of species and coordinate systems, for which an analytical form of the kinetic energy operator is not available.
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Affiliation(s)
- Frederik Bader
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
| | - David Lauvergnat
- Université Paris-Saclay, CNRS, Institut de Chimie Physique UMR8000, Orsay 91405, France.
| | - Ove Christiansen
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
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4
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Oenen K, Dinu DF, Liedl KR. Determining internal coordinate sets for optimal representation of molecular vibration. J Chem Phys 2024; 160:014104. [PMID: 38180253 DOI: 10.1063/5.0180657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/10/2023] [Indexed: 01/06/2024] Open
Abstract
Arising from the harmonic approximation in solving the vibrational Schrödinger equation, normal modes dissect molecular vibrations into distinct degrees of freedom. Normal modes are widely used as they give rise to descriptive vibrational notations and are convenient for expanding anharmonic potential energy surfaces as an alternative to higher-order Taylor series representations. Usually, normal modes are expressed in Cartesian coordinates, which bears drawbacks that can be overcome by switching to internal coordinates. Considering vibrational notations, normal modes with delocalized characters are difficult to denote, but internal coordinates offer a route to clearer notations. Based on the Hessian, normal mode decomposition schemes for a given set of internal coordinates can describe a normal mode by its contributions from internal coordinates. However, choosing a set of internal coordinates is not straightforward. While the Hessian provides unique sets of normal modes, various internal coordinate sets are possible for a given system. In the present work, we employ a normal mode decomposition scheme to choose an optimal set. Therefore, we screen reasonable sets based on topology and symmetry considerations and rely on a metric that minimizes coupling between internal coordinates. Ultimately, the Nomodeco toolkit presented here generates internal coordinate sets to find an optimal set for representing molecular vibrations. The resulting contribution tables can be used to clarify vibrational notations. We test our scheme on small to mid-sized molecules, showing how the space of definable internal coordinate sets can significantly be reduced.
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Affiliation(s)
- Kemal Oenen
- Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
| | - Dennis F Dinu
- Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
| | - Klaus R Liedl
- Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
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5
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Bader F, Lauvergnat D, Christiansen O. Vibrationally correlated calculations in polyspherical coordinates: Taylor expansion-based kinetic energy operators. J Chem Phys 2023; 159:214107. [PMID: 38047511 DOI: 10.1063/5.0171912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 11/06/2023] [Indexed: 12/05/2023] Open
Abstract
The efficiency of quantum chemical simulations of nuclear motion can in many cases greatly benefit from the application of curvilinear coordinate systems. This is rooted in the fact that a set of smartly selected curvilinear coordinates may represent the motion naturally well, thus decreasing the couplings between motions in these coordinates. In this study, we assess the validity of different Taylor expansion-based approximations of kinetic energy operators in a (curvilinear) polyspherical parametrization. To this end, we investigate the accuracy as well as the numerical performance of the approximations in time-independent vibrational coupled cluster and full vibrational interaction calculations for several test cases ranging from tri- to penta-atomic molecules. We find that several of the proposed schemes reproduce the vibrational ground state and excitation energies to a decent accuracy, justifying their application in future investigations. Furthermore, due to the restricted mode coupling and their inherent sum-of-products form, the new approximations open up the possibility of treating large molecular systems with efficient vibrational coupled cluster schemes in general coordinates.
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Affiliation(s)
- F Bader
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - D Lauvergnat
- Université Paris-Saclay, CNRS, Institut de Chimie Physique UMR8000, Orsay 91405, France
| | - O Christiansen
- Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
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6
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Ruiz J, Misa K, Seshappan A, Keçeli M, Sode O. Exploring the anharmonic vibrational structure of carbon dioxide trimers. J Chem Phys 2021; 154:144302. [PMID: 33858169 DOI: 10.1063/5.0039793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Our previously developed mbCO2 potential [O. Sode and J. N. Cherry, J. Comput. Chem. 38, 2763 (2017)] is used to describe the vibrational structure of the intermolecular motions of the CO2 trimers: barrel-shaped and cyclic trimers. Anharmonic corrections are accounted for using the vibrational self-consistent field theory, vibrational second-order Møller-Plesset perturbation (VMP2) theory, and vibrational configuration interaction (VCI) methods and compared with experimental observations. For the cyclic structure, we revise the assignments of two previously observed experimental peaks based on our VCI and VMP2 results. We note that the experimental band observed near 13 cm-1 is the out-of-phase out-of-plane degenerate motion with E″ symmetry, while the peak observed at 18 cm-1 likely corresponds to the symmetric out-of-plane torsion A″ vibration. Since the VCI treatment of the vibrational motions accounts for vibrational mixing and delocalization, overtones and combination bands were also observed and quantified in the intermolecular regions of the two trimer isomers.
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Affiliation(s)
- Jesus Ruiz
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, USA
| | - Kyle Misa
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, USA
| | - Arabi Seshappan
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, USA
| | - Murat Keçeli
- Computational Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Olaseni Sode
- Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, California 90032, USA
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7
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Abbott AS, Turney JM, Zhang B, Smith DGA, Altarawy D, Schaefer HF. PES-Learn: An Open-Source Software Package for the Automated Generation of Machine Learning Models of Molecular Potential Energy Surfaces. J Chem Theory Comput 2019; 15:4386-4398. [DOI: 10.1021/acs.jctc.9b00312] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Adam S. Abbott
- Center for Computational Quantum Chemistry, The University of Georgia, Athens, Georgia 30602, United States
| | - Justin M. Turney
- Center for Computational Quantum Chemistry, The University of Georgia, Athens, Georgia 30602, United States
| | - Boyi Zhang
- Center for Computational Quantum Chemistry, The University of Georgia, Athens, Georgia 30602, United States
| | - Daniel G. A. Smith
- Molecular Sciences Software Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Doaa Altarawy
- Molecular Sciences Software Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
- Computer and Systems Engineering Department, Alexandria University, Alexandria, Egypt
| | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, The University of Georgia, Athens, Georgia 30602, United States
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8
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Roy S, Maiti KS. Structural sensitivity of CH vibrational band in methyl benzoate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 196:289-294. [PMID: 29459159 DOI: 10.1016/j.saa.2018.02.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 02/08/2018] [Indexed: 06/08/2023]
Abstract
The CH vibrational bands of methyl benzoate are studied to understand its coupling pattern with other vibrational bands of the biological molecule. This will facilitate to understand the biological structure and dynamics in spectroscopic as well as in microscopic study. Due to the congested spectroscopic pattern, near degeneracy, and strong anharmonicity of the CH stretch vibrations, assignment of the CH vibrational frequencies are often misleading. Anharmonic vibrational frequency calculation with multidimensional potential energy surface interprets the CH vibrational spectra more accurately. In this article we have presented the importance of multidimensional potential energy surface in anharmonic vibrational frequency calculation and discuss the unexpected red shift of asymmetric CH stretch vibration of methyl group. The CD stretch vibrational band which is splitted to double peaks due to the Fermi resonance is also discussed here.
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Affiliation(s)
- Susmita Roy
- Die Klinik und Poliklinik für Orthopädie und Sportorthopädie, Technische Universität München, Ismaninger Straße 22, München D81675, Germany
| | - Kiran Sankar Maiti
- Lehrstuhl für Experimental Physik, Ludwig-Maximilians-Universität München, Am Couombwall 1, Garching 85748, Germany; Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, Garching 85748, Germany.
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9
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Petrenko T, Rauhut G. A General Approach for Calculating Strongly Anharmonic Vibronic Spectra with a High Density of States: The X̃2B1 ← X̃1A1 Photoelectron Spectrum of Difluoromethane. J Chem Theory Comput 2017; 13:5515-5527. [DOI: 10.1021/acs.jctc.7b00468] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Taras Petrenko
- Institute for Theoretical Chemistry, Pfaffenwaldring
55, 70569 Stuttgart, Germany
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, Pfaffenwaldring
55, 70569 Stuttgart, Germany
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10
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Bulik IW, Frisch MJ, Vaccaro PH. Vibrational self-consistent field theory using optimized curvilinear coordinates. J Chem Phys 2017; 147:044110. [DOI: 10.1063/1.4995440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ireneusz W. Bulik
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA
| | - Michael J. Frisch
- Gaussian, Inc., 340 Quinnipiac St. Bldg. 40, Wallingford, Connecticut 06492, USA
| | - Patrick H. Vaccaro
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA
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11
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Baiardi A, Stein CJ, Barone V, Reiher M. Vibrational Density Matrix Renormalization Group. J Chem Theory Comput 2017; 13:3764-3777. [DOI: 10.1021/acs.jctc.7b00329] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alberto Baiardi
- Scuola Normale
Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Christopher J. Stein
- Laboratorium
für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Vincenzo Barone
- Scuola Normale
Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Markus Reiher
- Laboratorium
für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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12
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Changala PB, Baraban JH. Ab initio effective rotational and rovibrational Hamiltonians for non-rigid systems via curvilinear second order vibrational Møller–Plesset perturbation theory. J Chem Phys 2016; 145:174106. [DOI: 10.1063/1.4966234] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- P. Bryan Changala
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Joshua H. Baraban
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
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13
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Monteiro JG, Barbosa AG. VSCF calculations for the intra- and intermolecular vibrational modes of the water dimer and its isotopologs. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2016.09.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Lauvergnat D, Luis JM, Kirtman B, Reis H, Nauts A. Numerical and exact kinetic energy operator using Eckart conditions with one or several reference geometries: Application to HONO. J Chem Phys 2016; 144:084116. [DOI: 10.1063/1.4942172] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Sibaev M, Crittenden DL. The PyPES library of high quality semi-global potential energy surfaces. J Comput Chem 2015; 36:2200-7. [DOI: 10.1002/jcc.24192] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 07/19/2015] [Accepted: 08/10/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Marat Sibaev
- Department of Chemistry; University of Canterbury; Christchurch New Zealand
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16
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Oschetzki D, Rauhut G. Pushing the limits in accurate vibrational structure calculations: anharmonic frequencies of lithium fluoride clusters (LiF)n, n = 2-10. Phys Chem Chem Phys 2015; 16:16426-35. [PMID: 24981078 DOI: 10.1039/c4cp02264e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The vibrational spectra of a series of small lithium fluoride clusters, i.e. (LiF)n, n = 2-10, were studied by vibrational configuration interaction (VCI) calculations relying on potential energy surfaces including three-mode coupling terms and being obtained from explicitly correlated local coupled cluster calculations. Due to the account for anharmonicity effects, the simulated spectra allow for a direct comparison with experimental data and may thus help to identify clusters in the experiments. Even structurally closely related clusters can clearly be distinguished by infrared spectroscopy. The largest system in this study required more than 1000 basis functions in the electronic structure calculations and more than 10(7) configurations in the vibrational structure calculations and became computationally feasible only due to a combination of different approximations and highly parallelized algorithms.
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Affiliation(s)
- Dominik Oschetzki
- Institute of Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart D-70569, Germany.
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17
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Cheng X, Steele RP. Efficient anharmonic vibrational spectroscopy for large molecules using local-mode coordinates. J Chem Phys 2015; 141:104105. [PMID: 25217902 DOI: 10.1063/1.4894507] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
This article presents a general computational approach for efficient simulations of anharmonic vibrational spectra in chemical systems. An automated local-mode vibrational approach is presented, which borrows techniques from localized molecular orbitals in electronic structure theory. This approach generates spatially localized vibrational modes, in contrast to the delocalization exhibited by canonical normal modes. The method is rigorously tested across a series of chemical systems, ranging from small molecules to large water clusters and a protonated dipeptide. It is interfaced with exact, grid-based approaches, as well as vibrational self-consistent field methods. Most significantly, this new set of reference coordinates exhibits a well-behaved spatial decay of mode couplings, which allows for a systematic, a priori truncation of mode couplings and increased computational efficiency. Convergence can typically be reached by including modes within only about 4 Å. The local nature of this truncation suggests particular promise for the ab initio simulation of anharmonic vibrational motion in large systems, where connection to experimental spectra is currently most challenging.
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Affiliation(s)
- Xiaolu Cheng
- 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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18
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Abstract
Methyl benzoate is studied as a model compound for the development of new IR pulse schemes with possible applicability to biomolecules.
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19
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Thomsen B, Yagi K, Christiansen O. Optimized coordinates in vibrational coupled cluster calculations. J Chem Phys 2014. [DOI: 10.1063/1.4870775] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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20
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Strobusch D, Scheurer C. Adaptive sparse grid expansions of the vibrational Hamiltonian. J Chem Phys 2014; 140:074111. [DOI: 10.1063/1.4864356] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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21
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Fábri C, Mátyus E, Császár AG. Numerically constructed internal-coordinate Hamiltonian with Eckart embedding and its application for the inversion tunneling of ammonia. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 119:84-89. [PMID: 23702049 DOI: 10.1016/j.saa.2013.03.090] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/26/2013] [Accepted: 03/28/2013] [Indexed: 06/02/2023]
Abstract
It is shown that the use of an Eckart-frame embedding with a kinetic energy operator expressed in curvilinear internal coordinates becomes feasible and straightforward to implement for arbitrary molecular compositions and internal coordinates if the operator is defined numerically over a (discrete variable representation) grid. The algorithm proposed utilizes the transformation method of Dymarsky and Kudin to maintain the rotational Eckart condition. In order to demonstrate the applicability and flexibility of our approach the non-rigid ammonia molecule is considered and the corresponding rotational-vibrational energy levels and wave functions are computed using kinetic energy operators with three different embeddings. Two of them fulfill the Eckart conditions corresponding to a trigonal pyramidal (C3v) and a trigonal planar (D3h) reference structure and the third one is a non-Eckart frame. The computed energy levels are, of course, identical, and the structure of the three different wave-function representations are analyzed in terms of the rigid rotor functions for a symmetric top. The possible advantages of one frame representation over another are discussed concerning the interpretation of the rovibrational states in terms of the traditional rigid rotor labels.
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Affiliation(s)
- Csaba Fábri
- Laboratory of Molecular Structure and Dynamics, Institute of Chemistry, Eötvös University, P.O. Box 32, H-1518 Budapest 112, Hungary
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22
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Mielke SL, Chakraborty A, Truhlar DG. Vibrational Configuration Interaction Using a Tiered Multimode Scheme and Tests of Approximate Treatments of Vibrational Angular Momentum Coupling: A Case Study for Methane. J Phys Chem A 2013; 117:7327-43. [DOI: 10.1021/jp4011789] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Steven L. Mielke
- Department of Chemistry
and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis,
Minnesota 55455-0431, United States
| | - Arindam Chakraborty
- Department of Chemistry
and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis,
Minnesota 55455-0431, United States
| | - Donald G. Truhlar
- Department of Chemistry
and Minnesota Supercomputing
Institute, University of Minnesota, Minneapolis,
Minnesota 55455-0431, United States
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23
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Strobusch D, Nest M, Scheurer C. The adaptive hierarchical expansion of the kinetic energy operator. J Comput Chem 2013; 34:1210-7. [DOI: 10.1002/jcc.23241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 01/07/2013] [Accepted: 01/12/2013] [Indexed: 11/11/2022]
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24
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Strobusch D, Scheurer C. A general nuclear motion Hamiltonian and non-internal curvilinear coordinates. J Chem Phys 2013; 138:094107. [DOI: 10.1063/1.4793627] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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25
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Meier P, Bellchambers G, Klepp J, Manby FR, Rauhut G. Modeling of high-order terms in potential energy surface expansions using the reference-geometry Harris–Foulkes method. Phys Chem Chem Phys 2013; 15:10233-40. [DOI: 10.1039/c3cp50172h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Christiansen O. Selected new developments in vibrational structure theory: potential construction and vibrational wave function calculations. Phys Chem Chem Phys 2012; 14:6672-87. [DOI: 10.1039/c2cp40090a] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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