The weak orthogonality functional in explicitly correlated pair theories

David P. Tew, Wim Klopper*, Frederick R. Manby

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

17 Citations (Scopus)

Abstract

Recent advances have seen the convergence of the R12 and Gaussian geminal explicitly correlated methods, such that the principal remaining distinction is the way in which the many-electron integrals are handled. Here we examine the weak orthogonality functional and the resolution of the identity and find that the first, although exact in the limit of infinite basis, introduces a conflict between the physical description of the electronic cusp and the satisfaction of the strong orthogonality constraint. This leads us to propose an improved weak orthogonality functional where the explicitly correlated pair functions are almost orthogonal to the occupied orbitals by construction. For applications where 95%-98% accuracy in the total correlation energy is sufficient, we recommend use of the strong orthogonality functional in combination with the resolution of the identity for three- and four-electron integral evaluations. (c) 2007 American Institute of Physics.

Original languageEnglish
Article number174105
Number of pages8
JournalJournal of Chemical Physics
Volume127
Issue number17
DOIs
Publication statusPublished - 7 Nov 2007

Keywords

  • NEON
  • ATOMS
  • COMPUTATION
  • MOLECULAR CALCULATIONS
  • 2ND-ORDER CORRELATION ENERGIES
  • GAUSSIAN-BASIS SETS
  • WAVE-FUNCTIONS
  • GEMINAL FUNCTIONS
  • QUANTUM-CHEMICAL CALCULATIONS
  • ELECTRONIC-STRUCTURE THEORY

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