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Shchepanovska D, Shannon RJ, Curchod BFE, Glowacki DR. Nonadiabatic Kinetics in the Intermediate Coupling Regime: Comparing Molecular Dynamics to an Energy-Grained Master Equation. J Phys Chem A 2021; 125:3473-3488. [PMID: 33880919 DOI: 10.1021/acs.jpca.1c01260] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We propose and test an extension of the energy-grained master equation (EGME) for treating nonadiabatic (NA) hopping between different potential energy surfaces, which enables us to model the competition between stepwise collisional relaxation and kinetic processes which transfer population between different electronic states of the same spin symmetry. By incorporating Zhu-Nakamura theory into the EGME, we are able to treat NA passages beyond the simple Landau-Zener approximation, along with the corresponding treatments of zero-point energy and tunneling probability. To evaluate the performance of this NA-EGME approach, we carried out detailed studies of the UV photodynamics of the volatile organic compound C6-hydroperoxy aldehyde (C6-HPALD) using on-the-fly ab initio molecular dynamics and trajectory surface hopping. For this multichromophore molecule, we show that the EGME is able to capture important aspects of the dynamics, including kinetic timescales, and diabatic trapping. Such an approach provides a promising and efficient strategy for treating the long-time dynamics of photoexcited molecules in regimes which are difficult to capture using atomistic on-the-fly molecular dynamics.
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Affiliation(s)
| | - Robin J Shannon
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | | | - David R Glowacki
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K.,Intangible Realities Laboratory, University of Bristol, Bristol BS8 1UB, U.K.,Department of Computer Science, University of Bristol, Bristol BS8 1UB, U.K
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2
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Lin KC, Muthiah B, Chang HP, Kasai T, Chang YP. Halogen-related photodissociation in atmosphere: characterisation of atomic halogen, molecular halogen, and hydrogen halide. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1822590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
| | | | - Hsiu-Pu Chang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Toshio Kasai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan
- Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan
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3
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Bacchus-Montabonel MC. Proton-induced collision dynamics on potential prebiotic sulfur species. Phys Chem Chem Phys 2018; 20:9084-9089. [PMID: 29561041 DOI: 10.1039/c8cp00886h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of the building blocks of life and how they could survive under harsh astrophysical environments remains an open question of prebiotic chemistry. Effectively, ion bombardments or intense UV radiation may drive the destruction of prebiotic compounds. The possible role of sulfur in such processes is addressed here for the first time, by comparing directly proton-induced charge transfer for sulfur containing molecules and that for related COMs. The proton collision on mercaptoacetonitrile HSCH2C[triple bond, length as m-dash]N conformers has thus been investigated theoretically in a wide impact energy range modelling various astrophysical environments and compared to related COMs, namely HCN oligomers, in order to exhibit qualitative tendencies.
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Affiliation(s)
- Basile F. E. Curchod
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Todd J. Martínez
- Department of Chemistry and PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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Calvo F, Bacchus-Montabonel MC. Size-Induced Segregation in the Stepwise Microhydration of Hydantoin and Its Role in Proton-Induced Charge Transfer. J Phys Chem A 2018; 122:1634-1642. [DOI: 10.1021/acs.jpca.7b10291] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Florent Calvo
- LiPhy, Université Grenoble 1 and CNRS UMR 5588, 140 Avenue
de la Physique, 38402 St Martin d’Hères, France
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Bacchus-Montabonel MC. Theoretical investigation of proton collisions on prebiotic candidates: hydrogen cyanide polymers. Phys Chem Chem Phys 2017; 19:19566-19572. [PMID: 28338703 DOI: 10.1039/c7cp00826k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
One of the major concerns in prebiotic chemistry is the formation and destruction routes of prebiotic compounds in space. As detected for a long time, hydrogen cyanide (HCN) has been suggested to be a feedstock molecule at the origin of life driving easy oligomerization, in particular to form adenine. This may focus on its first oligomers because its dimer cyanomethanimine was recently observed in star-forming regions, or its trimer aminomalononitrile. With regard to the assumption of an extra-terrestrial origin of life, the stability of such species under ultraviolet radiation or in ion-collisions is an open question. Thus, we investigated theoretically the proton collisions with dimer and trimer isomers of HCN in a wide impact energy range to model various astrophysical environments and exhibit qualitative tendencies.
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Mendive-Tapia D, Kortekaas L, Steen JD, Perrier A, Lasorne B, Browne WR, Jacquemin D. Accidental degeneracy in the spiropyran radical cation: charge transfer between two orthogonal rings inducing ultra-efficient reactivity. Phys Chem Chem Phys 2016; 18:31244-31253. [DOI: 10.1039/c6cp06907j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We unravel an original photoswitching mechanism in spiropyran radical cation.
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Affiliation(s)
- David Mendive-Tapia
- Institut Charles Gerhardt Montpellier
- UMR 5253
- CNRS-UM-ENSCM
- CTMM
- Université Montpellier
| | - Luuk Kortekaas
- Molecular Inorganic Chemistry
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- 9747AG Groningen
| | - Jorn D. Steen
- Molecular Inorganic Chemistry
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- 9747AG Groningen
| | - Aurélie Perrier
- Université Paris Diderot Sorbonne Paris Cité
- F-75205 Paris Cedex 13
- France
- Institut de Recherche de Chimie Paris
- PSL Research University
| | - Benjamin Lasorne
- Institut Charles Gerhardt Montpellier
- UMR 5253
- CNRS-UM-ENSCM
- CTMM
- Université Montpellier
| | - Wesley R. Browne
- Molecular Inorganic Chemistry
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- 9747AG Groningen
| | - Denis Jacquemin
- Chimie Et Interdisciplinarité
- Synthèse, Analyse, Modélisation (CEISAM)
- UMR CNRS no. 6230
- 44322 Nantes Cedex 3
- France
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Hsu MY, Tsai PY, Wei ZR, Chao MH, Zhang B, Kasai T, Lin KC. Competitive bond rupture in the photodissociation of bromoacetyl chloride and 2- and 3-bromopropionyl chloride: adiabatic versus diabatic dissociation. Chemphyschem 2013; 14:936-45. [PMID: 23400968 DOI: 10.1002/cphc.201200957] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Indexed: 11/08/2022]
Abstract
Competitive bond dissociation mechanisms for bromoacetyl chloride and 2- and 3-bromopropionyl chloride following the (1) [n(O)→π*(C=O)] transition at 234-235 nm are investigated. Branching ratios for C−Br/C−Cl bond fission are found by using the (2+1) resonance-enhanced multiphoton ionization (REMPI) technique coupled with velocity ion imaging. The fragment branching ratios depend mainly on the dissociation pathways and the distances between the orbitals of Br and the C=O chromophore. C−Cl bond fission is anticipated to follow an adiabatic potential surface for a strong diabatic coupling between the n(O)π*(C=O) and np (Cl)σ*(C−Cl) bands. In contrast, C−Br bond fission is subject to much weaker coupling between n(O)π*(C=O) and np (Br)σ*(C−Br). Thus, a diabatic pathway is preferred for bromoacetyl chloride and 2-bromopropionyl chloride, which leads to excited-state products. For 3-bromopropionyl chloride, the available energy is not high enough to reach the excited-state products such that C−Br bond fission must proceed through an adiabatic pathway with severe suppression by nonadiabatic coupling. The fragment translational energies and anisotropy parameters for the three molecules are also analyzed and appropriately interpreted.
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Affiliation(s)
- Ming-Yi Hsu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
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Cauët E, Carette T, Lauzin C, Li JG, Loreau J, Delsaut M, Nazé C, Verdebout S, Vranckx S, Godefroid M, Liévin J, Vaeck N. From atoms to biomolecules: a fruitful perspective. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1254-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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10
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Cui G, Sun Z, Fang W. Adiabatic and Nonadiabatic Bond Cleavages in Norrish Type I Reaction. J Phys Chem A 2011; 115:10146-53. [DOI: 10.1021/jp2053025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ganglong Cui
- Chemistry College, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Zhigang Sun
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Weihai Fang
- Chemistry College, Beijing Normal University, Beijing 100875, People's Republic of China
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11
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Bacchus-Montabonel MC. Radiative and collisional processes in space chemistry. RENDICONTI LINCEI-SCIENZE FISICHE E NATURALI 2011. [DOI: 10.1007/s12210-011-0115-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Lasorne B, Worth GA, Robb MA. Excited-state dynamics. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2011. [DOI: 10.1002/wcms.26] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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14
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Sumita M, Saito K. Ground state potential energy surface between cyclobutadiene and tetrahedrane looked down from S1/S0 conical intersections. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.04.083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Brogaard RY, Møller KB, Sølling TI. Wave Packet Simulation of Nonadiabatic Dynamics in Highly Excited 1,3-Dibromopropane. J Phys Chem A 2008; 112:10481-6. [DOI: 10.1021/jp805273w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Rasmus Y. Brogaard
- Center for Molecular Movies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø, Denmark, and Center for Molecular Movies, Department of Chemistry, Technical University of Denmark, DTU 207, DK-2800 Lyngby, Denmark
| | - Klaus B. Møller
- Center for Molecular Movies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø, Denmark, and Center for Molecular Movies, Department of Chemistry, Technical University of Denmark, DTU 207, DK-2800 Lyngby, Denmark
| | - Theis I. Sølling
- Center for Molecular Movies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø, Denmark, and Center for Molecular Movies, Department of Chemistry, Technical University of Denmark, DTU 207, DK-2800 Lyngby, Denmark
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Rozgonyi T, González L. A Two-Dimensional Wavepacket Study of the Nonadiabatic Dynamics of CH2BrCl. J Phys Chem A 2008; 112:5573-81. [DOI: 10.1021/jp8011427] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Tamás Rozgonyi
- Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri út 59-67, Hungary, Institut für Physikalische Chemie, Friedrich-Schiller Universität, Jena Helmholtzweg 4, 07743 Jena, Germany, and Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
| | - Leticia González
- Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri út 59-67, Hungary, Institut für Physikalische Chemie, Friedrich-Schiller Universität, Jena Helmholtzweg 4, 07743 Jena, Germany, and Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
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Valero R, Truhlar DG. A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics. J Phys Chem A 2007; 111:8536-51. [PMID: 17691756 DOI: 10.1021/jp072590u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A diabatic representation is convenient in the study of electronically nonadiabatic chemical reactions because the diabatic energies and couplings are smooth functions of the nuclear coordinates and the couplings are scalar quantities. A method called the fourfold way was devised in our group to generate diabatic representations for spin-free electronic states. One drawback of diabatic states computed from the spin-free Hamiltonian, called a valence diabatic representation, for systems in which spin-orbit coupling cannot be ignored is that the couplings between the states are not zero in asymptotic regions, leading to difficulties in the calculation of reaction probabilities and other properties by semiclassical dynamics methods. Here we report an extension of the fourfold way to construct diabatic representations suitable for spin-coupled systems. In this article we formulate the method for the case of even-electron systems that yield pairs of fragments with doublet spin multiplicity. For this type of system, we introduce the further simplification of calculating the triplet diabatic energies in terms of the singlet diabatic energies via Slater's rules and assuming constant ratios of Coulomb to exchange integrals. Furthermore, the valence diabatic couplings in the triplet manifold are taken equal to the singlet ones. An important feature of the method is the introduction of scaling functions, as they allow one to deal with multibond reactions without having to include high-energy diabatic states. The global transformation matrix to the new diabatic representation, called the spin-valence diabatic representation, is constructed as the product of channel-specific transformation matrices, each one taken as the product of an asymptotic transformation matrix and a scaling function that depends on ratios of the spin-orbit splitting and the valence splittings. Thus the underlying basis functions are recoupled into suitable diabatic basis functions in a manner that provides a multibond generalization of the switch between Hund's cases in diatomic spectroscopy. The spin-orbit matrix elements in this representation are taken equal to their atomic values times a scaling function that depends on the internuclear distances. The spin-valence diabatic potential energy matrix is suitable for semiclassical dynamics simulations. Diagonalization of this matrix produces the spin-coupled adiabatic energies. For the sake of illustration, diabatic potential energy matrices are constructed along bond-fission coordinates for the HBr and the BrCH(2)Cl molecules. Comparison of the spin-coupled adiabatic energies obtained from the spin-valence diabatics with those obtained by ab initio calculations with geometry-dependent spin-orbit matrix elements shows that the new method is sufficiently accurate for practical purposes. The method formulated here should be most useful for systems with a large number of atoms, especially heavy atoms, and/or a large number of spin-coupled electronic states.
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Affiliation(s)
- Rosendo Valero
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
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Lasorne B, Dive G, Desouter-Lecomte M. Wave packets in a bifurcating region of an energy landscape: Diels-Alder dimerization of cyclopentadiene. J Chem Phys 2007; 122:184304. [PMID: 15918701 DOI: 10.1063/1.1891726] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantum dynamics in a valley ridge inflection (VRI) point region is analyzed in the case of the Diels-Alder endo-dimerization of cyclopentadiene pointed out recently by [Caramella et al., J. Am. Chem. Soc. 124, 1130 (2002)]. The VRI point is located along the reaction path connecting the bispericyclic symmetrical transition structure put in evidence by Caramella et al. and the transition state of the Cope rearrangement. Dynamics is carried out by using constrained Hamiltonian methodology. The active coordinates are the first formed C-C bond length and the difference between the two other C-C bond lengths which achieve the dimerization as 4+2 or 2+4 adducts. A two-dimensional (2D) minimum-energy surface have been computed at the Becke 3 Lee-Yong-Parr6-31G* level. The energy landscape can be classified as an uphill ridge-pitchfork VRI bifurcation according to a recent classification of bifurcation events [W. Quapp, J. Mol. Struct. 695-696, 95 (2004)]. Dynamics does not describe the thermal reaction but concerns wave packets which could be prepared by pulse reagents, i.e., by coherent control. We analyze how the shape and initial location on the ground potential-energy surface are linked to the synchronous or asynchronous mechanism of the final step after the first transition state. We use a one-dimensional model of optimum control theory to check the feasibility of such a coherent preparation. The wave-packet evolution in the VRI domain is well explained by semiclassical predictions even with the negative curvature of the unstable ridge. Finally, a crude model of dissipation has been introduced to test the stability of the 2D predictions.
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Affiliation(s)
- B Lasorne
- Laboratoire de Chimie Physique [Unité Mixte de Recherche (UMR) 8000], Université Paris-Sud, Centre Scientifique d'Orsay, F-91405 Orsay Cedex, France
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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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Zhang F, Ding WJ, Fang WH. Combined nonadiabatic transition-state theory and ab initio molecular dynamics study on selectivity of the α and β bond fissions in photodissociation of bromoacetyl chloride. J Chem Phys 2006; 125:184305. [PMID: 17115750 DOI: 10.1063/1.2371044] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The selectivity of the alpha C-Cl and beta C-Br bond fissions upon n-->pi(*) excitation of bromoacetyl chloride has been investigated with combined nonadiabatic Rice-Ramsperger-Kassel-Marcus theory and ab initio molecular dynamics calculations, which are based on the potential energy profiles calculated with the complete active space self-consistent field and multireference configuration interaction methods. The Zhu-Nakamura [J. Chem. Phys. 101, 10630 (1994); 102, 7448 (1995)] theory is chosen to calculate the nonadiabatic hopping probability. It is found that nonadiabatic effect plays an important role in determining selective dissociations of the C-Cl and C-Br bonds. The calculated rate constants are close to those from experimentally inferred values, but the branching ratio of the alpha C-Cl and beta C-Br bond fissions is different from the experimental findings. The direct molecular dynamics calculations predict that fission of the C-Cl bond occurs on a time scale of picoseconds and cleavage of the beta C-Br bond proceeds with less probability within the same period. This reveals that the initial relaxation dynamics is probably another important factor that influences the selectivity of the C-Cl and C-Br bond fissions in photodissociation of BrCH(2)COCl at 248 nm.
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Affiliation(s)
- Feng Zhang
- Department of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
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Lauvergnat D, Baloïtcha E, Dive G, Desouter-Lecomte M. Dynamics of complex molecular systems with numerical kinetic energy operators in generalized coordinates. Chem Phys 2006. [DOI: 10.1016/j.chemphys.2006.03.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Blancafort L, Hunt P, Robb MA. Intramolecular Electron Transfer in Bis(methylene) Adamantyl Radical Cation: A Case Study of Diabatic Trapping. J Am Chem Soc 2005; 127:3391-9. [PMID: 15755157 DOI: 10.1021/ja043879h] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Our characterization of the potential energy surface for electron transfer (ET) in the bis(methylene)adamantane (BMA) model radical cation shows that the surface topology is prone to diabatic trapping (competition between ET and upward hops to the excited state). The general conditions for this phenomenon have been derived. The surface is centered around a conical intersection, and diabatic trapping occurs because one of the branching space coordinates (coordinates that lift the degeneracy at first order) corresponds to a vector of small length. For BMA, this coordinate is an antisymmetric breathing mode of the rigid carbon framework. Other modes (including methylene torsions and pyramidalizations) may lift the degeneracy at second-order but do not affect the energy gap at the intersection region effectively. The resulting topology is similar to that of an (n - 1) dimensional seam (where n is the number of nuclear degrees of freedom of the molecule) that cannot be avoided along the reaction coordinate, thus favoring recrossing to the upper surface. This analysis is extended by ab initio semiclassical dynamics using an Ehrenfest and a trajectory surface hopping algorithm implemented at the CASSCF level. Examination of the trajectories shows that there is no single mode that controls the diabatic trap, in agreement with the condition that there is no predominant degeneracy-lifting coordinate. Thus the reactivity depends on a combination of small effects, where presumably higher-order effects come into play. This should be the general behavior of dynamics at a diabatic trapping situation.
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Affiliation(s)
- Lluís Blancafort
- Institut de Química Computacional and Departament de Química, Universitat de Girona, E-17071 Girona, Spain.
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