Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation

Xia, Shu-Hua; Liu, Xiang-Yang; Fang, Qiu; Cui, Ganglong

doi:10.1063/1.4935598

Title: Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation

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Abstract

In this work, we have first employed the combined quantum mechanics/molecular mechanics (QM/MM) method to study the photodissociation mechanism of thioacetic acid CH{sub 3}C(O)SH in the S{sub 1}, T{sub 1}, and S{sub 0} states in argon matrix. CH{sub 3}C(O)SH is treated quantum mechanically using the complete active space self-consistent field and complete active space second-order perturbation theory methods; argon matrix is described classically using Lennard-Jones potentials. We find that the C-S bond fission is predominant due to its small barriers of ca. 3.0 and 1.0 kcal/mol in the S{sub 1} and T{sub 1} states. It completely suppresses the nearby C—C bond fission. After the bond fission, the S{sub 1} radical pair of CH{sub 3}CO and SH can decay to the S{sub 0} and T{sub 1} states via internal conversion and intersystem crossing, respectively. In the S{sub 0} state, the radical pair can either recombine to form CH{sub 3}C(O)SH or proceed to form molecular products of CH{sub 2}CO and H{sub 2}S. We have further employed our recently developed QM/MM generalized trajectory-based surface-hopping method to simulate the photodissociation dynamics of CH{sub 3}C(O)SH. In 1 ps dynamics simulation, 56% trajectories stay at the Franck-Condon region; the S{sub 1} C—S bond fission takes placemore »« less

Authors:

Xia, Shu-Hua; Liu, Xiang-Yang; Fang, Qiu; Cui, Ganglong ^[1]

Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China)

Publication Date:: Sat Nov 21 00:00:00 EST 2015

OSTI Identifier:: 22493252

Resource Type:: Journal Article

Journal Name:: Journal of Chemical Physics

Additional Journal Information:: Journal Volume: 143; Journal Issue: 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ARGON; CARBONYLS; COMPARATIVE EVALUATIONS; DISSOCIATION; HYDROGEN SULFIDES; INTERNAL CONVERSION; LENNARD-JONES POTENTIAL; ORGANIC ACIDS; PERTURBATION THEORY; PHOTOLYSIS; QUANTUM MECHANICS; RADICALS; SELF-CONSISTENT FIELD; SURFACES

Citation Formats


                    Xia, Shu-Hua, Liu, Xiang-Yang, Fang, Qiu, and Cui, Ganglong. Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation.  United States: N. p., 2015. 
        Web.  doi:10.1063/1.4935598.

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                    Xia, Shu-Hua, Liu, Xiang-Yang, Fang, Qiu, & Cui, Ganglong. Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation.  United States.  https://doi.org/10.1063/1.4935598

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                    Xia, Shu-Hua, Liu, Xiang-Yang, Fang, Qiu, and Cui, Ganglong. 2015.  
        "Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation".  United States.  https://doi.org/10.1063/1.4935598.

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@article{osti_22493252,

  title        = {Photodissociation dynamics of CH{sub 3}C(O)SH in argon matrix: A QM/MM nonadiabatic dynamics simulation},

  author       = {Xia, Shu-Hua and Liu, Xiang-Yang and Fang, Qiu and Cui, Ganglong},

  abstractNote = {In this work, we have first employed the combined quantum mechanics/molecular mechanics (QM/MM) method to study the photodissociation mechanism of thioacetic acid CH{sub 3}C(O)SH in the S{sub 1}, T{sub 1}, and S{sub 0} states in argon matrix. CH{sub 3}C(O)SH is treated quantum mechanically using the complete active space self-consistent field and complete active space second-order perturbation theory methods; argon matrix is described classically using Lennard-Jones potentials. We find that the C-S bond fission is predominant due to its small barriers of ca. 3.0 and 1.0 kcal/mol in the S{sub 1} and T{sub 1} states. It completely suppresses the nearby C—C bond fission. After the bond fission, the S{sub 1} radical pair of CH{sub 3}CO and SH can decay to the S{sub 0} and T{sub 1} states via internal conversion and intersystem crossing, respectively. In the S{sub 0} state, the radical pair can either recombine to form CH{sub 3}C(O)SH or proceed to form molecular products of CH{sub 2}CO and H{sub 2}S. We have further employed our recently developed QM/MM generalized trajectory-based surface-hopping method to simulate the photodissociation dynamics of CH{sub 3}C(O)SH. In 1 ps dynamics simulation, 56% trajectories stay at the Franck-Condon region; the S{sub 1} C—S bond fission takes place in the remaining 44% trajectories. Among all nonadiabatic transitions, the S{sub 1} → S{sub 0} internal conversion is major (55%) but the S{sub 1} → T{sub 1} intersystem crossing is still comparable and cannot be ignored, which accounts for 28%. Finally, we have found a radical channel generating the molecular products of CH{sub 2}CO and H{sub 2}S, which is complementary to the concerted molecular channel. The present work sets the stage for simulating photodissociation dynamics of similar thio-carbonyl systems in matrix.},

  doi          = {10.1063/1.4935598},

  url          = {https://www.osti.gov/biblio/22493252},
  journal      = {Journal of Chemical Physics},

  issn         = {0021-9606},

  number       = 19,

  volume       = 143,

  place        = {United States},

  year         = {Sat Nov 21 00:00:00 EST 2015},

  month        = {Sat Nov 21 00:00:00 EST 2015}

}

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