Chen Zhenhua, Zhou Chen, Wu Wei
The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and College of Chemistry and Chemical Engineering, Xiamen University , Xiamen, Fujian 361005, China.
J Chem Theory Comput. 2015 Sep 8;11(9):4102-8. doi: 10.1021/acs.jctc.5b00416. Epub 2015 Aug 5.
In this work, a hierarchy of valence bond (VB) methods based on the concept of seniority number, defined as the number of singly occupied orbitals in a determinant or an orbital configuration, is proposed and applied to the studies of the potential energy curves (PECs) of H8, N2, and C2 molecules. It is found that the seniority-based VB expansion converges more rapidly toward the full configuration interaction (FCI) or complete active space self-consistent field (CASSCF) limit and produces more accurate PECs with smaller nonparallelity errors than its molecular orbital (MO) theory-based analogue. Test results reveal that the nonorthogonal orbital-based VB theory provides a reverse but more efficient way to truncate the complete active Hilbert space by seniority numbers.
在这项工作中，提出了一种基于资历数概念的价键（VB）方法层次结构，资历数定义为行列式或轨道构型中单个占据轨道的数量，并将其应用于研究H8、N2和C2分子的势能曲线（PEC）。研究发现，基于资历数的VB展开向全组态相互作用（FCI）或完全活性空间自洽场（CASSCF）极限收敛得更快，并且比基于分子轨道（MO）理论的类似物产生更精确的PEC，且非平行误差更小。测试结果表明，基于非正交轨道的VB理论提供了一种相反但更有效的方法，通过资历数来截断完全活性希尔伯特空间。
