Key Laboratory of Mesoscopic Chemistry, Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
J Chem Phys. 2012 Jan 21;136(3):034302. doi: 10.1063/1.3676725.
State-to-state photodissociation dynamics of H(2)O in its B band has been investigated quantum mechanically on a new set of non-adiabatically coupled potential energy surfaces for the lowest two (1)A' states of H(2)O, which are developed at the internally contracted multi-reference configuration interaction level with the aug-cc-pVQZ basis set. Quantum dynamical calculations carried out using the Chebyshev propagator yield absorption spectra, product state distributions, branching ratios, and differential cross sections, which are in reasonably good agreement with the latest experimental results. Particular focus is placed here on the dependence of various dynamical observables on the photon energy. Detailed analyses of the dynamics have assigned the diffuse structure in absorption spectrum to short-time recurring dynamics near the HOH conical intersection. The non-adiabatic dissociation to the ground state OH product via the HOH conical intersection is facile, direct, fast, and produces rotationally hot OH(X̃) products. On the other hand, the adiabatic channel on the excited state leading to the OH(Ã) product is dominated by long-lived resonances, which depend sensitively on the potential energy surfaces.
采用内收缩多参考组态相互作用方法在 aug-cc-pVQZ 基组上对 H(2)O 的最低两个（1）A'态构建了一套新的非绝热耦合势能面，对 H(2)O 的 B 带进行了量子力学态态光解动力学研究。利用切比雪夫传播子进行量子动力学计算，得到了吸收光谱、产物态分布、分支比和微分截面，这些结果与最新的实验结果相当吻合。特别关注了各种动力学观测值对光子能量的依赖性。通过分析动力学，确定了吸收光谱中弥散结构归因于 HOH 锥形交叉附近短时间内的周期性动力学。通过 HOH 锥形交叉非绝热解离到基态 OH 产物是容易的、直接的、快速的，并且产生了转动热的 OH(X̃)产物。另一方面，通向 OH(Ã)产物的激发态的绝热通道主要由长寿命共振主导，这对势能面非常敏感。
