Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Chem Phys. 2017 Feb 14;146(6):064301. doi: 10.1063/1.4975121.
Analytic potential energy surfaces (PESs) and state couplings of the ground and two lowest singlet excited states of thioanisole (CHSCH) are constructed in a diabatic representation based on electronic structure calculations including dynamic correlation. They cover all 42 internal degrees of freedom and a wide range of geometries including the Franck-Condon region and the reaction valley along the breaking S-CH bond with the full ranges of the torsion angles. The parameters in the PESs and couplings are fitted to the results of smooth diabatic electronic structure calculations including dynamic electron correlation by the extended multi-configurational quasi-degenerate perturbation theory method for the adiabatic state energies followed by diabatization by the fourfold way. The fit is accomplished by the anchor points reactive potential method with two reactive coordinates and 40 nonreactive degrees of freedom, where the anchor-point force fields are obtained with a locally modified version of the QuickFF package. The PESs and couplings are suitable for study of the topography of the trilayer potential energy landscape and for electronically nonadiabatic molecular dynamics simulations of the photodissociation of the S-CH bond.
基于电子结构计算（包括动态相关），构建了噻吩（CHSCH）基态和两个最低单重激发态的解析势能面（PES）和态耦合，采用非绝热表示。它们涵盖了所有 42 个内部分子自由度和广泛的几何形状，包括 Franck-Condon 区域和沿 S-CH 键断裂的反应谷，涵盖了扭转角的全范围。PES 和耦合中的参数通过扩展的多组态准简并微扰理论方法拟合到包括动态电子相关的光滑非绝热电子结构计算结果，该方法用于绝热态能量，然后通过四步法进行非绝热化。拟合通过带有两个反应坐标和 40 个非反应自由度的锚点反应势能方法完成，其中锚点力场是使用 QuickFF 包的本地修改版本获得的。PES 和耦合适用于研究三层势能面的地形，以及用于 S-CH 键光解的非绝热分子动力学模拟。
