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Assessing the performance of trajectory surface hopping methods: Ultrafast internal conversion in pyrazine

Xie, Weiwei; Sapunar, Marin; Došlić, Nađa; Sala, Matthieu; Domcke, Wolfgang (2019) Assessing the performance of trajectory surface hopping methods: Ultrafast internal conversion in pyrazine. Journal of Chemical Physics, 150 (15). ISSN 0021-9606

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Trajectory surface hopping (TSH) methods have been widely used to study photoinduced nonadiabatic processes. In the present study, nonadiabatic dynamics simulations with the widely used Tully’s fewest switches surface hopping (FSSH) algorithm and a Landau-Zener-type TSH (LZSH) algorithm have been performed for the internal conversion dynamics of pyrazine. The accuracy of the two TSH algorithms has been critically evaluated by a direct comparison with exact quantum dynamics calculations for a model of pyrazine. The model comprises the three lowest excited electronic states (B3u(nπ*), A1u(nπ*), and B2u(ππ*)) and the nine most relevant vibrational degrees of freedom. Considering photoexcitation to the diabatic B2u(ππ*) state, we examined the time-dependent diabatic and adiabatic electronic population dynamics. It is found that the diabatic populations obtained with both TSH methods are in good agreement with the exact quantum results. Fast population oscillations between the B3u(nπ*) and A1u(nπ*) states, which reflect nonadiabatic electronic transitions driven by coherent dynamics in the normal mode Q8a, are qualitatively reproduced by both TSH methods. In addition to the model study, the TSH methods have been interfaced with the second-order algebraic diagrammatic construction ab initio electronic-structure method to perform full-dimensional on-the-fly nonadiabatic dynamics simulations for pyrazine. It is found that the electronic population dynamics obtained with the LZSH method is in excellent agreement with that obtained by the FSSH method using a local diabatization algorithm. Moreover, the electronic populations of the full-dimensional on-the-fly calculations are in excellent agreement with the populations of the three-state nine-mode model, which confirms that the internal conversion dynamics of pyrazine is accurately represented by this reduced-dimensional model on the time scale under consideration (200 fs). The original FSSH method, in which the electronic wave function is propagated in the adiabatic representation, yields less accurate results. The oscillations in the populations of the diabatic B3u(nπ*) and A1u(nπ*) states driven by the mode Q8a are also observed in the full-dimensional dynamics simulations.

Item Type: Article
Additional Information: W. Xie acknowledges support by an Alexander von Humboldt postdoctoral fellowship and by a research grant of the Deutsche Forschungsgemeinschaft. M. Sapunar and N. Dogli acknowledge support by the Croation Science Foundation (Grant No. IP-2016-06-1142) and computing time provided by the Croatian National Grid Infrastructure (Cro-NGI). N. Doglik and W. Domcke gratefully acknowledge support by an Institute Partnership Grant of the Alexander von Humboldt Foundation. M. Sala acknowledges support by a postdoctoral fellowship of the Alexander von Humboldt Foundation.
Uncontrolled Keywords: surface hopping ; pyrazine
Subjects: NATURAL SCIENCES > Chemistry
NATURAL SCIENCES > Chemistry > Physical Chemistry
NATURAL SCIENCES > Chemistry > Theoretical Chemistry
Divisions: Division of Physical Chemistry
Project titleProject leaderProject codeProject type
Svjetlo na molekulama: istraživanje spregnute elektronske i nuklearne dinamike-LightMolNađa DošlićIP-2016-06-1142HRZZ
Depositing User: Marin Sapunar
Date Deposited: 29 Nov 2019 12:59
DOI: 10.1063/1.5084961

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