A Practical Valence Bond Method: A Configuration Interaction Method Approach with Perturbation Theoretic Facility

Lingchun Song, Wei Wu*, Qianer Zhang, Sason Shaik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

The previously developed valence bond configuration interaction (VBCI) method (Wu, W.; Song, L.; Cao, Z.; Zhang, Q.; Shaik, S., J. Phys. Chem. A, 2002, 105, 2721) that borrows the general CI philosophy of the MO theory, is further extended in this article, and its methodological features are improved, resulting in three accurate and cost-effective procedures: (a) the effect of quadruplet excitation is incorporated using the Davidson correction, such that the new procedure reduces size consistency problems, with due improvement in the quality of the computational results, (b) A cost-effective procedure, named VBCI(D, S), is introduced. It includes doubly excited structures for active electrons and singly excited structures for inactive pairs. The computational results of VBCI(D, S) match those of VBCISD with much less computational effort than VBCISD. (c) Finally, a second-order perturbation theory is utilized as a means of configuration selection, and lead to considerable reduction of the computational cost, with little or no loss in accuracy. Applications of the new procedures to bond energies and barriers of chemical reactions are presented and discussed.

Original languageEnglish
Pages (from-to)472-478
Number of pages7
JournalJournal of Computational Chemistry
Volume25
Issue number4
DOIs
StatePublished - Mar 2004

Keywords

  • Configuration interaction method
  • Perturbation theory
  • Valence bond method

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