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Pandey A, Poirier B, Liang R. Development of Parallel On-the-Fly Crystal Algorithm for Global Exploration of Conical Intersection Seam Space. J Chem Theory Comput 2024; 20:4778-4789. [PMID: 38775818 DOI: 10.1021/acs.jctc.4c00292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Conical intersection (CI) seams are configuration spaces of a molecular system where two or more (spin) adiabatic electronic states are degenerate in energy. They play essential roles in photochemistry because nonradiative decays often occur near the minima of the seam, i.e., the minimum energy CIs (MECIs). Thus, it is important to explore the CI seams and discover the MECIs. Although various approaches exist for CI seam exploration, most of them are local in nature, requiring reasonable initial guesses of geometries and nuclear gradients during the search. Global search algorithms, on the other hand, are powerful because they can fully sample the configurational space and locate important MECIs missed by local algorithms. However, global algorithms are often computationally expensive for large systems due to their poor scalability with respect to the number of degrees of freedom. To overcome this challenge, we develop the parallel on-the-fly Crystal algorithm to globally explore the CI seam space, taking advantage of its superior scaling behavior. Specifically, Crystal is coupled with on-the-fly evaluations of the excited and ground state energies using multireference electronic structure methods. Meanwhile, the algorithm is parallelized to further boost its computational efficiency. The effectiveness of this new algorithm is tested for three types of molecular photoswitches of significant importance in material and biomedical sciences: photostatin (PST), stilbene, and butadiene. A rudimentary implementation of the algorithm is applied to PST and stilbene, resulting in the discovery of all previously identified MECIs and several new ones. A refined version of the algorithm, combined with a systematic clustering technique, is applied to butadiene, resulting in the identification of an unprecedented number of energetically accessible MECIs. The results demonstrate that the parallel on-the-fly Crystal algorithm is a powerful tool for automated global CI seam exploration.
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Affiliation(s)
- Ankit Pandey
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Bill Poirier
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Ruibin Liang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
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2
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Takayanagi T. Application of Reaction Path Search Calculations to Potential Energy Surface Fits. J Phys Chem A 2021; 125:3994-4002. [PMID: 33915053 DOI: 10.1021/acs.jpca.1c01512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There has been significant progress in recent years in the use of machine learning techniques to model high-dimensional reactive potential energy surfaces using large-scale data obtained from ab initio electronic structure calculations. In these methods, the strategy used to gather data becomes a key issue as the molecular size increases. In this work, we examine the applicability of the reaction path search algorithm implemented in the Global Reaction Route Mapping (GRRM) code as a data-gathering approach. The electronic energies and gradients sampled by using the GRRM calculation are directly used in potential energy surface fitting to a permutationally invariant polynomial function. This simple approach was applied to the HNS and HCNO reaction systems, and we found that the fitted potential energy surfaces reasonably reproduce the features of the electronic structure calculations used in the GRRM calculations. This suggests that the GRRM sampling scheme can be used to construct an initial potential energy surface.
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Affiliation(s)
- Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Saitama City, Saitama 338-8570, Japan
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3
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Schmitz G, Klinting EL, Christiansen O. A Gaussian process regression adaptive density guided approach for potential energy surface construction. J Chem Phys 2020; 153:064105. [DOI: 10.1063/5.0015344] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Gunnar Schmitz
- Department of Chemistry, Aarhus Universitet, DK-8000 Aarhus, Denmark
| | | | - Ove Christiansen
- Department of Chemistry, Aarhus Universitet, DK-8000 Aarhus, Denmark
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Pandey A, Poirier B. Plumbing Potentials for Molecules with Up To Tens of Atoms: How to Find Saddle Points and Fix Leaky Holes. J Phys Chem Lett 2020; 11:6468-6474. [PMID: 32687368 DOI: 10.1021/acs.jpclett.0c01435] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Potential energy surfaces (PESs) play an indispensable role in molecular dynamics but are notoriously difficult to flesh out properly in large-dimensional spaces. In particular, the undetected presence of PES holes, i.e., unphysical saddle points beyond which the potential energy drops arbitrarily, can have devastating effects on both classical and quantum dynamics calculations. In this study, the Crystal algorithm is developed as a tool for efficiently and accurately finding PES holes, as well as legitimate saddle points, even in very large-dimensional configuration spaces. The approach is applied to three large-dimensional PESs for molecular systems of current interest: uracil, naphthalene, and formic acid dimer. Low-lying PES holes are discovered and located for the first two systems-including naphthalene, for which no holes were previously suspected, to the best of our knowledge. Likewise, the double-well, double-proton-transfer isomerization saddle point for formic acid dimer is also located.
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Affiliation(s)
- Ankit Pandey
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - Bill Poirier
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
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Meyer KAE, Suhm MA. Stretching of cis-formic acid: warm-up and cool-down as molecular work-out. Chem Sci 2019; 10:6285-6294. [PMID: 31341581 PMCID: PMC6598513 DOI: 10.1039/c9sc01555h] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 05/15/2019] [Indexed: 01/17/2023] Open
Abstract
A new technique to rotationally simplify and Raman-probe conformationally and vibrationally excited small molecules is applied to the cis-trans isomerism of formic acid. It quintuples the previously available gas phase vibrational data base on this excited form of a strongly anharmonic planar molecule despite its limited spectral resolution. The newly determined cis-formic acid fundamentals allow for a balanced vibrational benchmark on both rotamers of formic acid. Assuming the adequacy of vibrational perturbation theory, it reveals weaknesses of standard methods for these systems like B3LYP-D3(BJ)/aVQZ VPT2 or PBE0-D3(BJ)/aVQZ VPT2. The functionals ωB97-XD and M06-2X additionally suffer from severe integration grid size and symmetry dependencies. The vibrational benchmark suggests B2PLYP-D3(BJ)/aVQZ VPT2 and MP2/aVQZ VPT2 as partially competitive and in any case efficient alternatives to computationally demanding coupled cluster vibrational configuration interaction calculations. Whether this is due to fortuitous compensation between electronic structure and vibrational perturbation error remains to be explored.
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Affiliation(s)
- Katharina A E Meyer
- Institut für Physikalische Chemie , Georg-August-Universität Göttingen , Tammannstr. 6 , 37077 Göttingen , Germany . ; ; Tel: +49 55139 33111
| | - Martin A Suhm
- Institut für Physikalische Chemie , Georg-August-Universität Göttingen , Tammannstr. 6 , 37077 Göttingen , Germany . ; ; Tel: +49 55139 33111
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Tew DP, Mizukami W. Ab Initio Vibrational Spectroscopy of cis- and trans-Formic Acid from a Global Potential Energy Surface. J Phys Chem A 2016; 120:9815-9828. [DOI: 10.1021/acs.jpca.6b09952] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David P. Tew
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | - Wataru Mizukami
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
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Ohno K. Study of Potential Energy Surfaces towards Global Reaction Route Mapping. CHEM REC 2016; 16:2198-2218. [PMID: 27059804 DOI: 10.1002/tcr.201500284] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Indexed: 11/11/2022]
Abstract
The potential energy surface (PES) is just a theoretical construct based on the Born-Oppenheimer approximation, but it underlies various phenomena, including molecular vibrations, collisional ionizations, and chemical reactions. This account describes how a new idea for global reaction route mapping (GRRM), which had seemed to be impossible for chemical systems with more than three atoms, was born and has been developed during the course of the study of the PES. GRRM has pioneered new fields of chemistry. Furthermore, techniques for GRRM are still developing, and GRRM is further extending its application to various areas of chemistry and chemical physics.
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Affiliation(s)
- Koichi Ohno
- Institute for Quantum Chemical Exploration, Minato-ku, Tokyo, 108-0022, Japan.
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Maeda S, Taketsugu T, Morokuma K, Ohno K. Anharmonic Downward Distortion Following for Automated Exploration of Quantum Chemical Potential Energy Surfaces. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2014. [DOI: 10.1246/bcsj.20140189] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Satoshi Maeda
- Department of Chemistry, Faculty of Science, Hokkaido University
| | | | - Keiji Morokuma
- Fukui Institute for Fundamental Chemistry, Kyoto University
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University
| | - Koichi Ohno
- Graduate School of Science, Tohoku University
- Institute for Quantum Chemical Exploration
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9
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Mizukami W, Tew DP. A second-order multi-reference perturbation method for molecular vibrations. J Chem Phys 2013; 139:194108. [DOI: 10.1063/1.4830100] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Maeda S, Ohno K, Morokuma K. Systematic exploration of the mechanism of chemical reactions: the global reaction route mapping (GRRM) strategy using the ADDF and AFIR methods. Phys Chem Chem Phys 2013; 15:3683-701. [DOI: 10.1039/c3cp44063j] [Citation(s) in RCA: 358] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Richter F, Carbonniere P, Dargelos A, Pouchan C. An adaptive potential energy surface generation method using curvilinear valence coordinates. J Chem Phys 2012; 136:224105. [DOI: 10.1063/1.4724305] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Lees RM, Sun ZD, Billinghurst BE. High-resolution spectroscopy of the C–N stretching band of methylamine. J Chem Phys 2011; 135:104306. [DOI: 10.1063/1.3633699] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Ehara M, Oyagi F, Abe Y, Fukuda R, Nakatsuji H. Excited-state geometries and vibrational frequencies studied using the analytical energy gradients of the direct symmetry-adapted cluster–configuration interaction method. I. HAX-type molecules. J Chem Phys 2011; 135:044316. [DOI: 10.1063/1.3617233] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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Ab initio anharmonic calculations of vibrational frequencies of benzene by means of efficient construction of potential energy functions. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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15
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Sokolov VV. Molecular dynamics simulation of liquid methanol. II. Unified assignment of infrared, raman, and sum frequency generation vibrational spectra in methyl C–H stretching region. J Chem Phys 2011; 134:024510. [DOI: 10.1063/1.3514146] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Das A, Mukhopadhyay D, Adhikari S, Baer M. Renner-Teller intersections along the collinear axes of polyatomic molecules: H2CN as a case study. J Chem Phys 2010; 133:084107. [PMID: 20815560 DOI: 10.1063/1.3479399] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The tetra-atomic C(2)H(2)(+) cation is known to form Renner-Teller-type intersections along its collinear axis. Not too long ago, we studied the nonadiabatic coupling terms (NACTs) of this molecule [G. J. Halász et al., J. Chem. Phys. 126, 154309 (2007)] and revealed two kinds of intersections. (i) By employing one of the hydrogens as a test particle, we revealed the fact that indeed the corresponding (angular) NACTs produce topological (Berry) phases that are equal to 2pi, which is a result anticipated in the case of Renner-Teller intersections. (ii) However, to our big surprise, repeating this study when one of the atoms (in this case a hydrogen) is shifted from the collinear arrangement yields for the corresponding topological phase a value that equals pi (and not 2pi). In other words, shifting (even slightly) one of the atoms from the collinear arrangement causes the intersection to change its character and become a Jahn-Teller intersection. This somewhat unexpected novel result was later further analyzed and confirmed by other groups [e.g., T. Vertesi and R. Englman, J. Phys. B 41, 025102 (2008)]. The present article is devoted to another tetra-atomic molecule, namely, the H(2)CN molecule, which just like the C(2)H(2)(+) ion, is characterized by Renner-Teller intersections along its collinear axis. Indeed, we revealed the existence of Renner-Teller intersections along the collinear axis, but in contrast to the C(2)H(2)(+) case a shift of one atom from the collinear arrangement did not form Jahn-Teller intersections. What we found instead is that the noncollinear molecule was not affected by the shift and kept its Renner-Teller character. Another issue treated in this article is the extension of (the two-state) Berry (topological) phase to situations with numerous strongly interacting states. So far the relevance of the Berry phase was tested for systems characterized by two isolated interacting states, although it is defined for any number of interacting states [M. V. Berry, Proc. R. Soc. London, Ser. A 392, 45 (1984)]. We intend to show how to overcome this limitation and get a valid, fully justified definition of a Berry phase for an isolated system of any number of interacting states (as is expected).
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Affiliation(s)
- Anita Das
- Department of Chemistry, University of Calcutta, Kolkata 700 009, India
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17
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Maeda S, Matsuda Y, Mizutani S, Fujii A, Ohno K. Long-Range Migration of a Water Molecule To Catalyze a Tautomerization in Photoionization of the Hydrated Formamide Cluster. J Phys Chem A 2010; 114:11896-9. [DOI: 10.1021/jp107034y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Satoshi Maeda
- Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192, Japan and Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Yoshiyuki Matsuda
- Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192, Japan and Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Shinichi Mizutani
- Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192, Japan and Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Asuka Fujii
- Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192, Japan and Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Koichi Ohno
- Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192, Japan and Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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18
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Sun ZD, Lees RM, Xu LH. Precision Lamb-dip infrared spectra of the C–N stretching band of CH3NH2 with a CO2-laser/microwave-sideband spectrometer. J Chem Phys 2010; 132:194310. [PMID: 20499966 DOI: 10.1063/1.3427543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zhen-Dong Sun
- School of Physics, Shandong University, 250100 Jinan, People's Republic of China.
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Al-Jabour S, Baer M, Deeb O, Leibscher M, Manz J, Xu X, Zilberg S. Molecular Symmetry Properties of Conical Intersections and Nonadiabatic Coupling Terms: Theory and Quantum Chemical Demonstration for Cyclopenta-2,4-dienimine (C5H4NH). J Phys Chem A 2009; 114:2991-3010. [DOI: 10.1021/jp905038t] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S. Al-Jabour
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
| | - M. Baer
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
| | - O. Deeb
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
| | - M. Leibscher
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
| | - J. Manz
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
| | - X. Xu
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
| | - S. Zilberg
- Institut für Chemie und Biochemie, Freie Universität Berlin, Germany, Faculty of Pharmacy, Al-Quds University, Palestine, The Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, Israel, and Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Israel
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Seidler P, Kaga T, Yagi K, Christiansen O, Hirao K. On the coupling strength in potential energy surfaces for vibrational calculations. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.10.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Levi C, Halász GJ, Vibók A, Bar I, Zeiri Y, Kosloff R, Baer M. Intralines of quasi-conical intersections on torsion planes: methylamine as a case study. J Phys Chem A 2009; 113:6756-62. [PMID: 19462985 DOI: 10.1021/jp901072u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recently we reported on a novel feature associated with the intersection of the two lowest states (1)A' and (1)A'' of the methylamine (J. Chem. Phys. 2008, 128, 244302). We established the existence of a finite (closed) line of conical intersections (ci), namely, a finite seam, located in the HC-NHH symmetry plane, a line that is formed by moving a single hydrogen on that plane while locking the positions of the (six) other atoms. In the present article, this study is extended to the corresponding torsion planes formed by rotating the methyl group around the CN axis. The torsion planes, in contrast with the HC-NHH symmetry plane, do not satisfy the symmetry feature that enables the seam just mentioned. Nevertheless, the calculated nonadiabatic coupling terms (NACTs) resemble features similar to those encountered in the HC-NHH symmetry plane. Following a tedious numerical study supported by a theoretical model (Section III), it was verified that these NACTs may become similar to those on the symmetry plane, sometimes even to the level of almost no distinction, but lack one basic feature; namely, they are not singular and therefore do not form topological effects.
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Affiliation(s)
- C Levi
- Department of Physics, Ben-Gurion University, Beer Sheva, 84105, Israel
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22
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An adaptive density-guided approach for the generation of potential energy surfaces of polyatomic molecules. Theor Chem Acc 2009. [DOI: 10.1007/s00214-009-0532-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Njegic B, Gordon MS. Predicting accurate vibrational frequencies for highly anharmonic systems. J Chem Phys 2008; 129:164107. [DOI: 10.1063/1.2987712] [Citation(s) in RCA: 31] [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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Watanabe Y, Maeda S, Ohno K. Intramolecular vibrational frequencies of water clusters (H2O)n (n=2–5): Anharmonic analyses using potential functions based on the scaled hypersphere search method. J Chem Phys 2008; 129:074315. [DOI: 10.1063/1.2973605] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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26
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Levi C, Halász GJ, Vibók Á, Bar I, Zeiri Y, Kosloff R, Baer M. An intraline of conical intersections for methylamine. J Chem Phys 2008; 128:244302. [DOI: 10.1063/1.2943143] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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