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Marie A, Burton HGA. Excited States, Symmetry Breaking, and Unphysical Solutions in State-Specific CASSCF Theory. J Phys Chem A 2023; 127:4538-4552. [PMID: 37141564 DOI: 10.1021/acs.jpca.3c00603] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
State-specific electronic structure theory provides a route toward balanced excited-state wave functions by exploiting higher-energy stationary points of the electronic energy. Multiconfigurational wave function approximations can describe both closed- and open-shell excited states and avoid the issues associated with state-averaged approaches. We investigate the existence of higher-energy solutions in complete active space self-consistent field (CASSCF) theory and characterize their topological properties. We demonstrate that state-specific approximations can provide accurate higher-energy excited states in H2 (6-31G) with more compact active spaces than would be required in a state-averaged formalism. We then elucidate the unphysical stationary points, demonstrating that they arise from redundant orbitals when the active space is too large or symmetry breaking when the active space is too small. Furthermore, we investigate the singlet-triplet crossing in CH2 (6-31G) and the avoided crossing in LiF (6-31G), revealing the severity of root flipping and demonstrating that state-specific solutions can behave quasi-diabatically or adiabatically. These results elucidate the complexity of the CASSCF energy landscape, highlighting the advantages and challenges of practical state-specific calculations.
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Affiliation(s)
- Antoine Marie
- Physical and Theoretical Chemical Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
| | - Hugh G A Burton
- Physical and Theoretical Chemical Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
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2
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Wang M, Fang WH, Li C. Assessment of State-Averaged Driven Similarity Renormalization Group on Vertical Excitation Energies: Optimal Flow Parameters and Applications to Nucleobases. J Chem Theory Comput 2023; 19:122-136. [PMID: 36534617 DOI: 10.1021/acs.jctc.2c00966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We present a comprehensive excited-state benchmark for the state-averaged (SA) driven similarity renormalization group (DSRG) [Li, C.; Evangelista, F. A. J. Chem. Phys. 2018, 148, 124106]. Following the QUEST database [Véril, M.; Scemama, A.; Caffarel, M.; Lipparini, F.; Boggio-Pasqua, M.; Jacquemin, D.; Loos, P.-F. Wiley Interdiscip. Rev. Comput. Mol. Sci. 2021, 11, e1517], 280 vertical transition energies of 35 medium-sized molecules are computed using the SA-DSRG derived second- and third-order perturbation theories (PT2/PT3) along with a nonperturbative approach [sq-LDSRG(2)]. Comparing to the theoretical best estimates, the optimal flow parameter is found to be 0.35 and 2.0 Eh-2 for SA-DSRG-PT2 and SA-DSRG-PT3, respectively. For SA-sq-LDSRG(2), a flow parameter of 1.5 Eh-2 provides converged equations without compromising the accuracy. We then assess the accuracy of the SA-DSRG hierarchy using these parameters. The SA-DSRG-PT2 scheme outperforms the level-shifted CASPT2 by 0.10 eV in mean absolute error (MAE), yet this accuracy is slightly inferior than that of CASPT2 with the ionization-potential-electron-affinity shift. Both SA-DSRG-PT3 and SA-sq-LDSRG(2) yield a MAE of 0.10 eV, which is comparable to that of CASPT3 (0.09 eV). Finally, we compute vertical excitation energies of several low-lying singlet states of nucleobases. The SA-sq-LDSRG(2) approach provides highly accurate results for π → π* excitations, while n → π* transitions are better described by SA-DSRG-PT3.
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Affiliation(s)
- Meng Wang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Chenyang Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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3
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Matsika S. Electronic Structure Methods for the Description of Nonadiabatic Effects and Conical Intersections. Chem Rev 2021; 121:9407-9449. [PMID: 34156838 DOI: 10.1021/acs.chemrev.1c00074] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nonadiabatic effects are ubiquitous in photophysics and photochemistry, and therefore, many theoretical developments have been made to properly describe them. Conical intersections are central in nonadiabatic processes, as they promote efficient and ultrafast nonadiabatic transitions between electronic states. A proper theoretical description requires developments in electronic structure and specifically in methods that describe conical intersections between states and nonadiabatic coupling terms. This review focuses on the electronic structure aspects of nonadiabatic processes. We discuss the requirements of electronic structure methods to describe conical intersections and nonadiabatic couplings, how the most common excited state methods perform in describing these effects, and what the recent developments are in expanding the methodology and implementing nonadiabatic couplings.
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Affiliation(s)
- Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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4
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Chakravarti D, Hazra K, Kayal R, Sasmal S, Mukherjee D. Exploration of interlacing and avoided crossings in a manifold of potential energy curves by a unitary group adapted state specific multi-reference perturbation theory (UGA-SSMRPT). J Chem Phys 2021; 155:014101. [PMID: 34241385 DOI: 10.1063/5.0054731] [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 Unitary Group Adapted State-Specific Multi-Reference Perturbation Theory (UGA-SSMRPT2) developed by Mukherjee et al. [J. Comput. Chem. 36, 670 (2015)] has successfully realized the goal of studying bond dissociation in a numerically stable, spin-preserving, and size-consistent manner. We explore and analyze here the efficacy of the UGA-SSMRPT2 theory in the description of the avoided crossings and interlacings between a manifold of potential energy curves for states belonging to the same space-spin symmetry. Three different aspects of UGA-SSMRPT2 have been studied: (a) We introduce and develop the most rigorous version of UGA-SSMRPT2 that emerges from the rigorous version of UGA-SSMRCC utilizing a linearly independent virtual manifold; we call this the "projection" version of UGA-SSMRPT2 (UGA-SSMRPT2 scheme P). We compare and contrast this approach with our earlier formulation that used extra sufficiency conditions via amplitude equations (UGA-SSMRPT2 scheme A). (b) We present the results for a variety of electronic states of a set of molecules, which display the striking accuracy of both the two versions of UGA-SSMRPT2 with respect to three different situations involving weakly avoided crossings, moderate/strongly avoided crossings, and interlacing in a manifold of potential energy curves (PECs) of the same symmetry. Accuracy of our results has been benchmarked against IC-MRCISD + Q.
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Affiliation(s)
- Dibyajyoti Chakravarti
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, India
| | - Koustav Hazra
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, India
| | - Riya Kayal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, India
| | - Sudip Sasmal
- Physikalisch-Chemisches Institut, Universität Heidelberg, Heidelberg, Germany
| | - Debashis Mukherjee
- Centre for Quantum Engineering, Research, and Education (CQuERE), TCG-CREST, Kolkata, India
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5
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Lechner MH, Izsák R, Nooijen M, Neese F. A perturbative approach to multireference equation-of-motion coupled cluster. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1939185] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Marvin H. Lechner
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - Róbert Izsák
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, USA
| | - Marcel Nooijen
- Department of Chemistry, University of Waterloo, Waterloo, Canada
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
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6
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Chattopadhyay S. Single-Root Multireference Brillouin-Wigner Perturbative Approach to Excitation Energies. ACS OMEGA 2021; 6:1668-1686. [PMID: 33490826 PMCID: PMC7818614 DOI: 10.1021/acsomega.0c05714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 12/28/2020] [Indexed: 06/12/2023]
Abstract
The state-specific Brillouin-Wigner multireference perturbation theory [which employs Jeziorski-Monkhorst parametrization of the wave function] using improved virtual orbitals, denoted as IVO-BWMRPT, is applied to calculate excitation energies (EEs) for methylene, ethylene, trimethylenemethane, and benzyne systems exhibiting various degrees of diradical character. In IVO-BWMRPT, all of the parameters appearing in the wave function ansatz are optimized for a specific electronic state. For these systems, the IVO-BWMRPT method provides EEs that are in close agreement with the benchmark results and experiments, where available, indicating that the method does not introduce imbalance in the target-specific treatment of closed- and open-shell states involved. The good performance of the present methodology is primarily related to structural compactness of the formalism. Overall, present findings are encouraging for both further development of the approach and chemical applications on the energy differences of strongly correlated systems.
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Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology,
Shibpur, Howrah 711103, India
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7
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Burton HGA, Thom AJW. Reaching Full Correlation through Nonorthogonal Configuration Interaction: A Second-Order Perturbative Approach. J Chem Theory Comput 2020; 16:5586-5600. [DOI: 10.1021/acs.jctc.0c00468] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hugh G. A. Burton
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Alex J. W. Thom
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
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8
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Song C, Martínez TJ. Reduced scaling extended multi-state CASPT2 (XMS-CASPT2) using supporting subspaces and tensor hyper-contraction. J Chem Phys 2020; 152:234113. [PMID: 32571032 DOI: 10.1063/5.0007417] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We present a reduced scaling formulation of the extended multi-state CASPT2 (XMS-CASPT2) method, which is based on our recently developed state-specific CASPT2 (SS-CASPT2) formulation using supporting subspaces and tensor hyper-contraction. By using these two techniques, the off-diagonal elements of the effective Hamiltonian can be computed with only O(N3) operations and O(N2) memory, where N is the number of basis functions. This limits the overall computational scaling to O(N4) operations and O(N2) memory. Thus, excited states can now be obtained at the same reduced (relative to previous algorithms) scaling we achieved for SS-CASPT2. In addition, we also investigate how the energy denominators can be factorized with the Laplace quadrature when some of the denominators are negative, which is critical for excited state calculations. An efficient implementation of the method has been developed using graphical processing units while also exploiting spatial sparsity in tensor operations. We benchmark the accuracy of the new method by comparison to non-THC formulated XMS-CASPT2 for the excited states of various molecules. In our tests, the THC approximation introduces negligible errors (≈0.01 eV) compared to the non-THC reference method. Scaling behavior and computational timings are presented to demonstrate performance. The new method is also interfaced with quantum mechanics/molecular mechanics (QM/MM). In an example study of green fluorescent protein, we show how the XMS-CASPT2 potential energy surfaces and excitation energies are affected by increasing the size of the QM region up to 278 QM atoms with more than 2300 basis functions.
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Affiliation(s)
- Chenchen Song
- Department of Chemistry and the PULSE Institute, Stanford University, Stanford, California 94305, USA
| | - Todd J Martínez
- Department of Chemistry and the PULSE Institute, Stanford University, Stanford, California 94305, USA
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9
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Abstract
![]()
We
introduce a new variant of the complete active space second-order
perturbation theory (CASPT2) method that performs similarly to multistate
CASPT2 (MS-CASPT2) in regions of the potential energy surface where
the electronic states are energetically well separated and is akin
to extended MS-CASPT2 (XMS-CASPT2) in case the underlying zeroth-order
references are near-degenerate. Our approach follows a recipe analogous
to that of XMS-CASPT2 to ensure approximate invariance under unitary
transformations of the model states and a dynamic weighting scheme
to smoothly interpolate the Fock operator between state-specific and
state-average regimes. The resulting extended dynamically weighted
CASPT2 (XDW-CASPT2) methodology possesses the most desirable features
of both MS-CASPT2 and XMS-CASPT2, that is, the ability to provide
accurate transition energies and correctly describe avoided crossings
and conical intersections. The reliability of XDW-CASPT2 is assessed
on a number of molecular systems. First, we consider the dissociation
of lithium fluoride, highlighting the distinctive characteristics
of the new approach. Second, the invariance of the theory is investigated
by studying the conical intersection of the distorted allene molecule.
Finally, the relative accuracy in the calculation of vertical excitation
energies is benchmarked on a set of 26 organic compounds. We found
that XDW-CASPT2, albeit being only approximately invariant, produces
smooth potential energy surfaces around conical intersections and
avoided crossings, performing equally well to the strictly invariant
XMS-CASPT2 method. The accuracy of vertical transition energies is
almost identical to MS-CASPT2, with a mean absolute deviation of 0.01–0.02
eV, in contrast to 0.12 eV for XMS-CASPT2.
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Affiliation(s)
- Stefano Battaglia
- Department of Chemistry-BMC, Uppsala University, P.O. Box 576, SE-75123 Uppsala, Sweden
| | - Roland Lindh
- Department of Chemistry-BMC, Uppsala University, P.O. Box 576, SE-75123 Uppsala, Sweden
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10
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Li C, Evangelista FA. Multireference Theories of Electron Correlation Based on the Driven Similarity Renormalization Group. Annu Rev Phys Chem 2019; 70:245-273. [DOI: 10.1146/annurev-physchem-042018-052416] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The driven similarity renormalization group (DSRG) provides an alternative way to address the intruder state problem in quantum chemistry. In this review, we discuss recent developments of multireference methods based on the DSRG. We provide a pedagogical introduction to the DSRG and its various extensions and discuss its formal properties in great detail. In addition, we report several illustrative applications of the DSRG to molecular systems.
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Affiliation(s)
- Chenyang Li
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA; emails: ,
| | - Francesco A. Evangelista
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA; emails: ,
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Li C, Lindh R, Evangelista FA. Dynamically weighted multireference perturbation theory: Combining the advantages of multi-state and state-averaged methods. J Chem Phys 2019; 150:144107. [DOI: 10.1063/1.5088120] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Chenyang Li
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Roland Lindh
- Department of Chemistry–BMC, Uppsala University, P.O. Box 576, SE-75123 Uppsala, Sweden
- Uppsala Center for Computational Chemistry, Uppsala University, P.O. Box 576, SE-75123 Uppsala, Sweden
| | - Francesco A. Evangelista
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
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12
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Li C, Evangelista FA. Driven similarity renormalization group for excited states: A state-averaged perturbation theory. J Chem Phys 2018; 148:124106. [DOI: 10.1063/1.5019793] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Chenyang Li
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Francesco A. Evangelista
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
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13
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Pathak S, Lang L, Neese F. A dynamic correlation dressed complete active space method: Theory, implementation, and preliminary applications. J Chem Phys 2017; 147:234109. [DOI: 10.1063/1.5017942] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Shubhrodeep Pathak
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Lucas Lang
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
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14
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Schriber JB, Evangelista FA. Adaptive Configuration Interaction for Computing Challenging Electronic Excited States with Tunable Accuracy. J Chem Theory Comput 2017; 13:5354-5366. [DOI: 10.1021/acs.jctc.7b00725] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jeffrey B. Schriber
- Department of Chemistry and
Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Francesco A. Evangelista
- Department of Chemistry and
Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
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Yanai T, Saitow M, Xiong XG, Chalupský J, Kurashige Y, Guo S, Sharma S. Multistate Complete-Active-Space Second-Order Perturbation Theory Based on Density Matrix Renormalization Group Reference States. J Chem Theory Comput 2017; 13:4829-4840. [DOI: 10.1021/acs.jctc.7b00735] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Takeshi Yanai
- Department
of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, 444-8585 Aichi Japan
- The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Masaaki Saitow
- The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Xiao-Gen Xiong
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Jakub Chalupský
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16110 Prague 6, Czech Republic
| | - Yuki Kurashige
- Department
of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyou-ku, Kyoto 606-8520, Japan
- Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Sheng Guo
- Division
of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sandeep Sharma
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Boulder, Colorado 80302, United States
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16
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Sinha Ray S, Ghosh P, Chaudhuri RK, Chattopadhyay S. Improved virtual orbitals in state specific multireference perturbation theory for prototypes of quasidegenerate electronic structure. J Chem Phys 2017; 146:064111. [DOI: 10.1063/1.4975322] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Carlos Borin A, Mai S, Marquetand P, González L. Ab initio molecular dynamics relaxation and intersystem crossing mechanisms of 5-azacytosine. Phys Chem Chem Phys 2017; 19:5888-5894. [DOI: 10.1039/c6cp07919a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Nonadiabatic SHARC dynamics simulations reveal the molecular deformations involved in the photodeactivation pathways of 5-azacytosine.
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Affiliation(s)
- Antonio Carlos Borin
- Department of Fundamental Chemistry
- Institute of Chemistry
- University of São Paulo
- NAP-PhotoTech the USP Consortium for Photochemical Technology
- São Paulo
| | - Sebastian Mai
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- 1090 Vienna
- Austria
| | - Philipp Marquetand
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- 1090 Vienna
- Austria
| | - Leticia González
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- 1090 Vienna
- Austria
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18
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Sharma S, Jeanmairet G, Alavi A. Quasi-degenerate perturbation theory using matrix product states. J Chem Phys 2016; 144:034103. [DOI: 10.1063/1.4939752] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Molecular bases for the selection of the chromophore of animal rhodopsins. Proc Natl Acad Sci U S A 2015; 112:15297-302. [PMID: 26607446 DOI: 10.1073/pnas.1510262112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The functions of microbial and animal rhodopsins are triggered by the isomerization of their all-trans and 11-cis retinal chromophores, respectively. To lay the molecular basis driving the evolutionary transition from the all-trans to the 11-cis chromophore, multiconfigurational quantum chemistry is used to compare the isomerization mechanisms of the sensory rhodopsin from the cyanobacterium Anabaena PCC 7120 (ASR) and of the bovine rhodopsin (Rh). It is found that, despite their evolutionary distance, these eubacterial and vertebrate rhodopsins start to isomerize via distinct implementations of the same bicycle-pedal mechanism originally proposed by Warshel [Warshel A (1976) Nature 260:678-683]. However, by following the electronic structure changes of ASR (featuring the all-trans chromophore) during the isomerization, we find that ASR enters a region of degeneracy between the first and second excited states not found in Rh (featuring the 11-cis chromophore). We show that such degeneracy is modulated by the preorganized structure of the chromophore and by the position of the reactive double bond. It is argued that the optimization of the electronic properties of the chromophore, which affects the photoisomerization efficiency and the thermal isomerization barrier, provided a key factor for the emergence of the striking amino acid sequence divergence observed between the microbial and animal rhodopsins.
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20
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Giner E, Angeli C. Metal-ligand delocalization and spin density in the CuCl2 and [CuCl4]2− molecules: Some insights from wave function theory. J Chem Phys 2015; 143:124305. [DOI: 10.1063/1.4931639] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Emmanuel Giner
- Dipartimento di Scienze Chimiche e Famaceutiche, Universita di Ferrara, Via Fossato di Mortara 17, I-44121 Ferrara, Italy
| | - Celestino Angeli
- Dipartimento di Scienze Chimiche e Famaceutiche, Universita di Ferrara, Via Fossato di Mortara 17, I-44121 Ferrara, Italy
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Gozem S, Melaccio F, Valentini A, Filatov M, Huix-Rotllant M, Ferré N, Frutos LM, Angeli C, Krylov AI, Granovsky AA, Lindh R, Olivucci M. Shape of Multireference, Equation-of-Motion Coupled-Cluster, and Density Functional Theory Potential Energy Surfaces at a Conical Intersection. J Chem Theory Comput 2014; 10:3074-84. [PMID: 26588278 DOI: 10.1021/ct500154k] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We report and characterize ground-state and excited-state potential energy profiles using a variety of electronic structure methods along a loop lying on the branching plane associated with a conical intersection (CI) of a reduced retinal model, the penta-2,4-dieniminium cation (PSB3). Whereas the performance of the equation-of-motion coupled-cluster, density functional theory, and multireference methods had been tested along the excited- and ground-state paths of PSB3 in our earlier work, the ability of these methods to correctly describe the potential energy surface shape along a CI branching plane has not yet been investigated. This is the focus of the present contribution. We find, in agreement with earlier studies by others, that standard time-dependent DFT (TDDFT) does not yield the correct two-dimensional (i.e., conical) crossing along the branching plane but rather a one-dimensional (i.e., linear) crossing along the same plane. The same type of behavior is found for SS-CASPT2(IPEA=0), SS-CASPT2(IPEA=0.25), spin-projected SF-TDDFT, EOM-SF-CCSD, and, finally, for the reference MRCISD+Q method. In contrast, we found that MRCISD, CASSCF, MS-CASPT2(IPEA=0), MS-CASPT2(IPEA=0.25), XMCQDPT2, QD-NEVPT2, non-spin-projected SF-TDDFT, and SI-SA-REKS yield the expected conical crossing. To assess the effect of the different crossing topologies (i.e., linear or conical) on the PSB3 photoisomerization efficiency, we discuss the results of 100 semiclassical trajectories computed by CASSCF and SS-CASPT2(IPEA=0.25) for a PSB3 derivative. We show that for the same initial conditions, the two methods yield similar dynamics leading to isomerization quantum yields that differ by only a few percent.
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Affiliation(s)
- Samer Gozem
- Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43403, United States
| | - Federico Melaccio
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena , via A. Moro 2, I-53100 Siena, Italy
| | - Alessio Valentini
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena , via A. Moro 2, I-53100 Siena, Italy.,Departamento de Química Física, Universidad de Alcalá , E-28871 Alcalá de Henares, Madrid, Spain
| | - Michael Filatov
- Institut für Physikalische und Theoretische Chemie, Universität Bonn , Beringstrasse 4, 53115 Bonn, Germany
| | - Miquel Huix-Rotllant
- Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire , Marseille, France
| | - Nicolas Ferré
- Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire , Marseille, France
| | - Luis Manuel Frutos
- Departamento de Química Física, Universidad de Alcalá , E-28871 Alcalá de Henares, Madrid, Spain
| | - Celestino Angeli
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara , via Fossato di Mortara 17, I-44121 Ferrara, Italy
| | - Anna I Krylov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089-0482, United States
| | | | - Roland Lindh
- Department of Chemistry - Ångström, the Theoretical Chemistry Programme, POB 518, SE-751 20 Uppsala, Sweden
| | - Massimo Olivucci
- Department of Chemistry, Bowling Green State University , Bowling Green, Ohio 43403, United States.,Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena , via A. Moro 2, I-53100 Siena, Italy
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22
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Liu W, Hoffmann MR. SDS: the ‘static–dynamic–static’ framework for strongly correlated electrons. Theor Chem Acc 2014. [DOI: 10.1007/s00214-014-1481-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Coe JP, Paterson MJ. State-averaged Monte Carlo configuration interaction applied to electronically excited states. J Chem Phys 2013; 139:154103. [DOI: 10.1063/1.4824888] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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24
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Ioffe IN, Granovsky AA. Photoisomerization of Stilbene: The Detailed XMCQDPT2 Treatment. J Chem Theory Comput 2013; 9:4973-90. [PMID: 26583415 DOI: 10.1021/ct400647w] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the detailed XMCQDPT2/cc-pVTZ study of trans-cis photoisomerization in one of the core systems of both experimental and computational photochemistry-the stilbene molecule. For the first time, the potential energy surface (PES) of the S1 state has been directly optimized and scanned using a multistate multiconfiguration second-order perturbation theory. We characterize the trans-stilbene, pyramidalized (phantom), and DHP-cis-stilbene geometric domains of the S1 state and describe their stationary points including the transition states between them, as well as S1/S0 intersections. Also reported are the minima and the activation barriers in the ground state. Our calculations correctly predict the kinetic isotope effect due to H/D exchange at ethylenic hydrogens, the dynamic behavior of excited cis-stilbene, and trans-cis branching ratio after relaxation to S0 through a rather unsymmetric conical intersection. In general, the XMCQDPT2 results confirm the qualitative adequacy of the TDDFT (especially SF-TDDFT) picture of the excited stilbene but also reveal quantitative discrepancies that deserve further exploration.
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Affiliation(s)
- I N Ioffe
- Department of Chemistry, Lomonosov Moscow State University , Moscow, 119991, Russia
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25
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Malrieu JP, Caballol R, Calzado CJ, de Graaf C, Guihéry N. Magnetic interactions in molecules and highly correlated materials: physical content, analytical derivation, and rigorous extraction of magnetic Hamiltonians. Chem Rev 2013; 114:429-92. [PMID: 24102410 DOI: 10.1021/cr300500z] [Citation(s) in RCA: 282] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jean Paul Malrieu
- Laboratoire de Chimie et Physique Quantiques, Université de Toulouse 3 , 118 route de Narbonne, 31062 Toulouse, France
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26
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Mokambe RM, Hicks JM, Kerker D, Jiang W, Theis D, Chen Z, Khait YG, Hoffmann MR. GVVPT2 multireference perturbation theory study of selenium oxides. Mol Phys 2013. [DOI: 10.1080/00268976.2013.809163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Rashel M. Mokambe
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Jason M. Hicks
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Dana Kerker
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Wanyi Jiang
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Daniel Theis
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Zhenhua Chen
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Yuriy G. Khait
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
| | - Mark R. Hoffmann
- a Department of Chemistry , University of North Dakota , Grand Forks , North Dakota , USA
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27
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Sousa C, Tosoni S, Illas F. Theoretical Approaches to Excited-State-Related Phenomena in Oxide Surfaces. Chem Rev 2012. [DOI: 10.1021/cr300228z] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Carmen Sousa
- Departament de Química
Física and Institut de Química Teòrica i Computacional
(IQTCUB), Universitat de Barcelona, C/Martí
i Franquès 1, 08028 Barcelona, Spain
| | - Sergio Tosoni
- Departament de Química
Física and Institut de Química Teòrica i Computacional
(IQTCUB), Universitat de Barcelona, C/Martí
i Franquès 1, 08028 Barcelona, Spain
- Departamento de Química, Universidad de Las Palmas de Gran Canaria, Campus Universitario
de Tafira, 35017 Las Palmas de Gran Canaria, Spain
| | - Francesc Illas
- Departament de Química
Física and Institut de Química Teòrica i Computacional
(IQTCUB), Universitat de Barcelona, C/Martí
i Franquès 1, 08028 Barcelona, Spain
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28
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Gozem S, Huntress M, Schapiro I, Lindh R, Granovsky AA, Angeli C, Olivucci M. Dynamic Electron Correlation Effects on the Ground State Potential Energy Surface of a Retinal Chromophore Model. J Chem Theory Comput 2012; 8:4069-80. [DOI: 10.1021/ct3003139] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Samer Gozem
- Department of Chemistry, Bowling
Green State University, Bowling Green, Ohio 43403, United States
| | - Mark Huntress
- Department of Chemistry, Bowling
Green State University, Bowling Green, Ohio 43403, United States
| | - Igor Schapiro
- Department of Chemistry, Bowling
Green State University, Bowling Green, Ohio 43403, United States
| | - Roland Lindh
- Department of Chemistry −
Ångström, the Theoretical Chemistry Programme, POB 518,
SE-751 20 Uppsala, Sweden
| | | | - Celestino Angeli
- Dipartimento di
Chimica, Università
di Ferrara, via Borsari 46, I-44121 Ferrara, Italy
| | - Massimo Olivucci
- Department of Chemistry, Bowling
Green State University, Bowling Green, Ohio 43403, United States
- Dipartimento di Chimica, Università
di Siena, via De Gasperi 2, I-53100 Siena, Italy
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29
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Khait YG, Theis D, Hoffmann MR. Nonadiabatic coupling terms for the GVVPT2 variant of multireference perturbation theory. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2011.09.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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30
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State specific multireference Møller–Plesset perturbation theory: A few applications to ground, excited and ionized states. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2011.04.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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31
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West AC, Lynch JD, Sellner B, Lischka H, Hase WL, Windus TL. O + C2H4 potential energy surface: excited states and biradicals at the multireference level. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1123-0] [Citation(s) in RCA: 7] [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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32
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Roskop L, Gordon MS. Quasi-degenerate second-order perturbation theory for occupation restricted multiple active space self-consistent field reference functions. J Chem Phys 2011; 135:044101. [DOI: 10.1063/1.3609756] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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33
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Theis D, Khait YG, Hoffmann MR. GVVPT2 energy gradient using a Lagrangian formulation. J Chem Phys 2011; 135:044117. [DOI: 10.1063/1.3611049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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34
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Granovsky AA. Extended multi-configuration quasi-degenerate perturbation theory: The new approach to multi-state multi-reference perturbation theory. J Chem Phys 2011; 134:214113. [DOI: 10.1063/1.3596699] [Citation(s) in RCA: 519] [Impact Index Per Article: 39.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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35
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A Modern First-Principles View on Ligand Field Theory Through the Eyes of Correlated Multireference Wavefunctions. STRUCTURE AND BONDING 2011. [DOI: 10.1007/430_2011_57] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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36
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MAHAPATRA US, DATTA B, MUKHERJEE D. A state-specific multi-reference coupled cluster formalism with molecular applications. Mol Phys 2010. [DOI: 10.1080/002689798168448] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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37
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Mahapatra US, Chattopadhyay S, Chaudhuri RK. Second-order state-specific multireference Møller Plesset perturbation theory: Application to energy surfaces of diimide, ethylene, butadiene, and cyclobutadiene. J Comput Chem 2010; 32:325-37. [DOI: 10.1002/jcc.21624] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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38
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Sánchez-Sanz G, Seijo L, Barandiarán Z. Yb2+-doped SrCl2: Electronic structure of impurity states and impurity-trapped excitons. J Chem Phys 2010; 133:114509. [DOI: 10.1063/1.3475562] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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39
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Vancoillie S, Chalupský J, Ryde U, Solomon EI, Pierloot K, Neese F, Rulísek L. Multireference ab initio calculations of g tensors for trinuclear copper clusters in multicopper oxidases. J Phys Chem B 2010; 114:7692-702. [PMID: 20469875 DOI: 10.1021/jp103098r] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
EPR spectroscopy has proven to be an indispensable tool in elucidating the structure of metal sites in proteins. In recent years, experimental EPR data have been complemented by theoretical calculations, which have become a standard tool of many quantum chemical packages. However, there have only been a few attempts to calculate EPR g tensors for exchange-coupled systems with more than two spins. In this work, we present a quantum chemical study of structural, electronic, and magnetic properties of intermediates in the reaction cycle of multicopper oxidases and of their inorganic models. All these systems contain three copper(II) ions bridged by hydroxide or O(2-) anions and their ground states are antiferromagnetically coupled doublets. We demonstrate that only multireference methods, such as CASSCF/CASPT2 or MRCI can yield qualitatively correct results (compared to the experimental values) and consider the accuracy of the calculated EPR g tensors as the current benchmark of quantum chemical methods. By decomposing the calculated g tensors into terms arising from interactions of the ground state with the various excited states, the origin of the zero-field splitting is explained. The results of the study demonstrate that a truly quantitative prediction of the g tensors of exchange-coupled systems is a great challenge to contemporary theory. The predictions strongly depend on small energy differences that are difficult to predict with sufficient accuracy by any quantum chemical method that is applicable to systems of the size of our target systems.
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Affiliation(s)
- Steven Vancoillie
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Heverlee-Leuven, Belgium
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40
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Olsen S. A Modified Resonance-Theoretic Framework for Structure−Property Relationships in a Halochromic Oxonol Dye. J Chem Theory Comput 2010. [DOI: 10.1021/ct100001b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Seth Olsen
- Centre for Organic Photonics and Electronics, School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072 Australia
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41
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Chattopadhyay S, Mahapatra US, Chaudhuri RK. Study of equilibrium geometries of diradicaloid systems via state specific multireference Møller–Plesset perturbation theory (SS-MRMPPT). Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.02.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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42
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Sinha Mahapatra U, Chattopadhyay S, Chaudhuri RK. Study of the Ground State Dissociation of Diatomic Molecular Systems Using State-Specific Multireference Perturbation Theory: A Brillouin−Wigner Scheme. J Chem Theory Comput 2010; 6:662-82. [DOI: 10.1021/ct900452n] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Uttam Sinha Mahapatra
- Department of Physics, Taki Government College, Taki, North 24 Parganas-743429, India
| | - Sudip Chattopadhyay
- Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103, India
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43
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Sinha Mahapatra U, Chattopadhyay S, Chaudhuri RK. Second-Order State-Specific Multireference Møller−Plesset Perturbation Theory (SS-MRMPPT) Applied to Geometry Optimization. J Phys Chem A 2010; 114:3668-82. [DOI: 10.1021/jp911581f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Uttam Sinha Mahapatra
- Department of Physics, Taki Government College, Taki, North 24
Parganas-743429, India
| | - Sudip Chattopadhyay
- Department of Chemistry, Bengal Engineering and Science University,
Shibpur, Howrah 711103, India
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44
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Mahapatra US, Chattopadhyay S, Chaudhuri RK. Application of state-specific multireference Møller–Plesset perturbation theory to nonsinglet states. J Chem Phys 2009; 130:014101. [DOI: 10.1063/1.3043364] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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45
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Devarajan A, Gaenko AV, Khait YG, Hoffmann MR. Generalized van Vleck Perturbation Theory (GVVPT2) Study of the Excited States of Benzene and the Azabenzenes. J Phys Chem A 2008; 112:2677-82. [DOI: 10.1021/jp077702w] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ajitha Devarajan
- Chemistry Department, University of North Dakota, Grand Forks, North Dakota 58202, St. Petersburg State Institute of Technology (Technical University), 26 Moskovskii Ave, St. Petersburg 190013, Russia,and Russian Scientific Center “Applied Chemistry”, 14 Dobrolyubova Ave, St. Petersburg 197198, Russia
| | - Alexander V. Gaenko
- Chemistry Department, University of North Dakota, Grand Forks, North Dakota 58202, St. Petersburg State Institute of Technology (Technical University), 26 Moskovskii Ave, St. Petersburg 190013, Russia,and Russian Scientific Center “Applied Chemistry”, 14 Dobrolyubova Ave, St. Petersburg 197198, Russia
| | - Yuri G. Khait
- Chemistry Department, University of North Dakota, Grand Forks, North Dakota 58202, St. Petersburg State Institute of Technology (Technical University), 26 Moskovskii Ave, St. Petersburg 190013, Russia,and Russian Scientific Center “Applied Chemistry”, 14 Dobrolyubova Ave, St. Petersburg 197198, Russia
| | - Mark R. Hoffmann
- Chemistry Department, University of North Dakota, Grand Forks, North Dakota 58202, St. Petersburg State Institute of Technology (Technical University), 26 Moskovskii Ave, St. Petersburg 190013, Russia,and Russian Scientific Center “Applied Chemistry”, 14 Dobrolyubova Ave, St. Petersburg 197198, Russia
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46
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Roos BO, Andersson K, Fülscher MP, Malmqvist PÂ, Serrano-Andrés L, Pierloot K, Merchán M. Multiconfigurational Perturbation Theory: Applications in Electronic Spectroscopy. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141526.ch5] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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47
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Neese F, Petrenko T, Ganyushin D, Olbrich G. Advanced aspects of ab initio theoretical optical spectroscopy of transition metal complexes: Multiplets, spin-orbit coupling and resonance Raman intensities. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2006.05.019] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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48
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Valero R, Truhlar DG. Nonadiabatic effects in C–Br bond scission in the photodissociation of bromoacetyl chloride. J Chem Phys 2006; 125:194305. [PMID: 17129101 DOI: 10.1063/1.2363991] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bromoacetyl chloride photodissociation has been interpreted as a paradigmatic example of a process in which nonadiabatic effects play a major role. In molecular beam experiments by Butler and co-workers [J. Chem. Phys. 95, 3848 (1991); J. Chem. Phys. 97, 355 (1992)], BrCH2C(O)Cl was prepared in its ground electronic state (S0) and excited with a laser at 248 nm to its first excited singlet state (S1). The two main ensuing photoreactions are the ruptures of the C-Cl bond and of the C-Br bond. A nonadiabatic model was proposed in which the C-Br scission is strongly suppressed due to nonadiabatic recrossing at the barrier formed by the avoided crossing between the S1 and S2 states. Recent reduced-dimensional dynamical studies lend support to this model. However, another interpretation that has been given for the experimental results is that the reduced probability of C-Br scission is a consequence of incomplete intramolecular energy redistribution. To provide further insight into this problem, we have studied the energetically lowest six singlet electronic states of bromoacetyl chloride by using an ab initio multiconfigurational perturbative electronic structure method. Stationary points (minima and saddle points) and minimum energy paths have been characterized on the S0 and S1 potential energy surfaces. The fourfold way diabatization method has been applied to transform five adiabatic excited electronic states to a diabatic representation. The diabatic potential energy matrix of the first five excited singlet states has been constructed along several cuts of the potential energy hypersurfaces. The thermochemistry of the photodissociation reactions and a comparison with experimental translational energy distributions strongly suggest that nonadiabatic effects dominate the C-Br scission, but that the reaction proceeds along the energetically allowed diabatic pathway to excited-state products instead of being nonadiabatically suppressed. This conclusion is also supported by the low values of the diabatic couplings on the C-Br scission reaction path. The methodology established in the present study will be used for the construction of global potential energy surfaces suitable for multidimensional dynamics simulations to test these preliminary interpretations.
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Affiliation(s)
- Rosendo Valero
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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49
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Angeli C, Calzado CJ, Cimiraglia R, Malrieu JP. A convenient decontraction procedure of internally contracted state-specific multireference algorithms. J Chem Phys 2006; 124:234109. [PMID: 16821909 DOI: 10.1063/1.2202738] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Internally contracted state-specific multireference (MR) algorithms, either perturbative such as CASPT2 or NEVPT2, or nonperturbative such as contracted MR configuration interaction or MR coupled cluster, are computationally efficient but they may suffer from the internal contraction of the wave function in the reference space. The use of a low dimensional multistate model space only offers limited flexibility and is not always practicable. The present paper suggests a convenient state-specific procedure to decontract the reference part of the wave function from a series of state-specific calculations using slightly perturbed zero-order wave functions. The method provides an orthogonal valence bond reading of the ground state and an effective valence Hamiltonian, the excited roots of which are shown to be relevant. The orthogonal valence bond functions can be considered quasidiabatic states and the effective valence Hamiltonian gives therefore the quasidiabatic energies and the electronic coupling among the quasidiabatic states. The efficiency of the method is illustrated in two case problems where the dynamical correlation plays a crucial role, namely, the LiF neutral/ionic avoided crossing and the F(2) ground state wave function.
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Affiliation(s)
- Celestino Angeli
- Dipartimento di Chimica, Università di Ferrara, Via Borsari 46, I-44100 Ferrara, Italy.
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50
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Angeli C, Cimiraglia R, Malrieu JP. A Simple Approximate Perturbation Approach to Quasi-degenerate Systems. Theor Chem Acc 2006. [DOI: 10.1007/s00214-006-0095-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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