Université de Toulouse, UPS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, 118, rte de Narbonne F-31062 Toulouse Cedex, France.
J Chem Phys. 2011 Jul 7;135(1):014101. doi: 10.1063/1.3600351.
A selected multireference configuration interaction (CI) method and the corresponding code are presented. It is based on a procedure of localization that permits to obtain well localized occupied and virtual orbitals. Due to the local character of the electron correlation, using local orbitals allows one to neglect long range interactions. In a first step, three topological matrices are constructed, which determine whether two orbitals must be considered as interacting or not. Two of them concern the truncation of the determinant basis, one for occupied/virtual, the second one for dispersive interactions. The third one concerns the truncation of the list of two electron integrals. This approach permits a fine analysis of each kind of approximation and induces a huge reduction of the CI size and of the computational time. The procedure is tested on linear polyene aldehyde chains, dissociation potential energy curve, and reaction energy of a pesticide-Ca(2+) complex and finally on transition energies of a large iron system presenting a light-induced excited spin-state trapping effect.
本文提出了一种选择的多参考组态相互作用（CI）方法和相应的代码。它基于一种局域化程序，允许获得良好局域化的占据和虚拟轨道。由于电子相关的局域性质，使用局域轨道可以忽略长程相互作用。在第一步中，构建了三个拓扑矩阵，它们决定两个轨道是否必须被认为是相互作用的。其中两个涉及行列式基的截断，一个用于占据/虚拟轨道，另一个用于分散相互作用。第三个矩阵涉及双电子积分列表的截断。这种方法允许对每种近似进行精细分析，并导致 CI 大小和计算时间的巨大减少。该程序在线性聚烯醛链、离解势能曲线、杀虫剂-Ca(2+)配合物的反应能以及具有光诱导激发自旋态捕获效应的大型铁体系的跃迁能方面进行了测试。
