Seniority Number in Valence Bond Theory

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• 作者：Zhenhua Chen ; Chen Zhou ; Wei Wu
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2015
• 出版时间：September 8, 2015
• 年：2015
• 卷：11
• 期：9
• 页码：4102-4108
• 全文大小：387K
• ISSN：1549-9626

文摘

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.