Nonsymmuetrical perturbation theory for improving coupled-cluster wave functions

James Whittaker

Research output: Contribution to journalArticle

6 Scopus citations


A general nonsymmetrical formulation of muldreference perturbation theory (PT) is used to correct the energy and wave function obtained from limited coupled-cluster (CC) calculations. Following the spirit of CC theory, we use the Hartree-Fock wave function in bras while the CC wave function is used as the ket reference. The resulting PT is compared to the symmetrical (Hermitean) formulation and to the systematic CC(n)PT(m) theory of Hirata et al. Numerical results up to the fifth order in PT are obtained in a determinantal formalism for a few sample molecules. The effect of partitioning is also studied.

Original languageEnglish (US)
Pages (from-to)1309-1320
Number of pages12
JournalInternational Journal of Quantum Chemistry
Issue number4-5
Publication statusPublished - Nov 15 2002



  • Coupled-cluster calculations
  • Nonsymmetrical perturbation theory
  • Partitioning

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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