Multiconfiguration perturbation theory: Size consistency at second order

Gnes Szabados, Zoltán Rolik, Gábor Tóth, Ṕter R. Surján

Research output: Article

50 Citations (Scopus)


A modified version of a previously elaborated multiconfiguration perturbation theory (MCPT) [Rolik J. Chem. Phys. 119, 1922 (2003)] is presented. In the modified formulation size consistency is ensured at second order in energy, by omitting projectors from the zero order Hamiltonian operator. This MCPT formulation is abbreviated as SC2-MCPT (size consistent at second order). To ensure proper separability, we also require that energy denominators are constructed as differences of some one-particle energies. A similar choice for energy denominators also renders the well-known multireference Møller-Plesset (MRMP) energy size consistent at second order. The same thing applies to the related multireference perturbation theory by Witek, Nakano, and Hirao.

Original languageEnglish
Article number114104
JournalJournal of Chemical Physics
Issue number11
Publication statusPublished - márc. 15 2005

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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