Lehrstuhl für Theoretische Chemie, Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen, Germany.
J Chem Phys. 2019 Sep 21;151(11):114105. doi: 10.1063/1.5112178.
The performance of Møller-Plesset perturbation theory methods for describing intermolecular interaction energies has been investigated with the focus on illuminating the impact of individual electron correlation energy contributions in fourth order. It is shown that a physically meaningful decomposition of the fourth order correlation energy can be obtained by grouping individual correlation energy terms that share the same diagrammatic loop structure. This decomposition of the fourth order singles (S), doubles (D), triples (T), and quadruples (Q) terms revealed that individual terms from each excitation class can have a huge impact on the energy that is much larger than the total fourth order correlation contribution. A partial summation of S, D, and Q terms has been derived that can reproduce the full fourth order interaction energies with a good accuracy and which does not include the computationally expensive triples energy term.
我们研究了Møller-Plesset 微扰理论方法在描述分子间相互作用能方面的性能，重点是阐明第四阶中单个电子相关能量贡献的影响。结果表明，可以通过对具有相同图式环结构的单个相关能量项进行分组，得到第四阶相关能量的物理意义上的分解。这种对第四阶单激发（S）、双激发（D）、三激发（T）和四激发（Q）项的分解表明，每个激发态类别的单个项都可能对能量产生巨大影响，其影响比第四阶总相关贡献还要大。我们推导出了 S、D 和 Q 项的部分求和，该求和可以以很好的精度重现完整的第四阶相互作用能，并且不包括计算成本高昂的三激发能量项。
