A quasi-complete active space self-consistent field method

Haruyuki Nakano, Kimihiko Hirao

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


A multi-configuration self-consistent field method is proposed in which a quasi-complete active space, which is the product space of complete active spaces, is used as a variational space. The computational effort for wavefunctions is significantly reduced compared with the complete active space self-consistent field (CAS-SCF) method. Efficient formulae with segmented alpha and beta strings are derived. The scheme is tested on the spectroscopic constants and a potential energy curve of CO, the transition state barrier height of the reaction, H2CO→H2+CO, and the energy difference between trans- and cis-butadiene. The results are in good agreement with the corresponding CAS-SCF results.

Original languageEnglish
Pages (from-to)90-96
Number of pages7
JournalChemical Physics Letters
Issue number1-2
Publication statusPublished - Jan 28 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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