多组态密度泛函理论及透热与绝热势能面的构建

Multistate Density Function Theory and the Construction of Diabatic and Adiabatic Potential Energy Surfaces

介绍一种基于价键理论框架的多组态密度泛函理论(MSDFT),并以氢气(H2)分子解离过程及硝酸(HNO3)分子在水溶液中的质子转移过程为例,阐述了MSDFT方法的有效性.结果表明,对于H2分子的解离过程,MSDFT方法克服了以往单行列式密度泛函理论(DFT)的弊端,可给出正确的解离曲线,同时由于通过组态相互作用引入了静态电子相关的贡献,其计算精度可接近CASPT2水平;对于HNO3分子在水溶液中的质子转移过程,MSDFT方法可直接构建质子转移的透热势能曲线以及相应的非绝热耦合矩阵元,另一方面通过引入离子组态的贡献,可显著提升其计算精度,使其计算结果与精确结果相吻合.

A multistate density function theory （MSDFT） based on valence bond theory was introduced. As an application, the MSDFT method was illustrated by the bond dissociation of H2 and the proton transfer between HNO3 and a water molecule. In the dissociation of H2, the MSDFF method yields a correct behavior as the two H atoms stretch to infinity, and gives a potential well in accord with second-order perturbation using complete active space（CASPT2）. For the proton transfer process of HNO3 , MSDFF can be used to yield both diabatic and adiabatic potential energy curves as a function of the proton transfer reaction coordinate. For the reaction barrier height, the inclusion of an ionic state in a three-state model can significantly improve the accuracy in barrier height in comparison with the high-level results.