Novel orthogonalization and biorthogonalization algorithms: Towards multistate multiconfiguration perturbation theory

Zsuzsanna Tóth, Péter R. Nagy, Péter Jeszenszki, Ágnes Szabados

Research output: Contribution to journalArticle

4 Citations (Scopus)


Orthogonalization with the prerequisite of keeping several vectors fixed is examined. Explicit formulae are derived both for orthogonal and biorthogonal vector sets. Calculation of the inverse or square root of the entire overlap matrix is eliminated, allowing computational time reduction. In this special situation, it is found sufficient to evaluate the functions of matrices of the dimension matching the number of fixed vectors. The (bi)orthogonal sets find direct application in extending multiconfigurational perturbation theory to deal with multiple reference vectors.

Original languageEnglish
Article number100
JournalTheoretical Chemistry Accounts
Issue number8
Publication statusPublished - Aug 4 2015



  • Biorthogonal sets
  • Multiconfiguration perturbation theory
  • Multistate theory
  • Orthogonalization
  • Overlap

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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