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Issue 29, 2017
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Nonadiabatic dynamics simulation of keto isocytosine: a comparison of dynamical performance of different electronic-structure methods

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Abstract

The nonadiabatic dynamics of keto isocytosine in the gas phase has been investigated using the on-the-fly trajectory surface hopping method based on two electronic-structure methods: SA-CASSCF and ADC(2). The results estimate an excited-state lifetime of around 1000 fs at the SA-CASSCF level, while a much shorter lifetime of 250–350 fs is obtained at the ADC(2) level. Although three conical intersections (CIs) (Ethyl. I, Ethyl. II and C[double bond, length as m-dash]O stretching) are relevant to the nonadiabatic decay of keto isocytosine, their contributions to the nonadiabatic decay are highly dependent on the electronic-structure methods employed in the dynamics simulation. The Ethyl. II CI is the main channel in the dynamics simulations at the SA-CASSCF level, while the C[double bond, length as m-dash]O stretching CI becomes dominant at the ADC(2) levels. Other high-level electronic-structure methods (MR-CISD and MS-CASPT2) are involved to benchmark our dynamics results. Through the analysis of the reaction pathways from the ground state minimum to the relevant CIs, we expect that the excited-state dynamical features obtained at the MR-CISD and MS-CASPT2 levels should be very similar to those at the SA-CASSCF level. The comparison of results obtained using different excited-state electronic-structure methods could provide guidance for further studies of similar systems.

Graphical abstract: Nonadiabatic dynamics simulation of keto isocytosine: a comparison of dynamical performance of different electronic-structure methods

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Publication details

The article was received on 18 Mar 2017, accepted on 23 Jun 2017 and first published on 27 Jun 2017


Article type: Paper
DOI: 10.1039/C7CP01732D
Citation: Phys. Chem. Chem. Phys., 2017,19, 19168-19177
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    Nonadiabatic dynamics simulation of keto isocytosine: a comparison of dynamical performance of different electronic-structure methods

    D. Hu, Y. F. Liu, A. L. Sobolewski and Z. Lan, Phys. Chem. Chem. Phys., 2017, 19, 19168
    DOI: 10.1039/C7CP01732D

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