Theoretica chimica acta

, Volume 93, Issue 6, pp 343–366

Modern valence bond representations of CASSCF wavefunctions

  • Thorstein Thorsteinsson
  • David L. Cooper
  • Joseph Gerratt
  • Peter B. Karadakov
  • Mario Raimondi
Article

DOI: 10.1007/BF01129215

Cite this article as:
Thorsteinsson, T., Cooper, D.L., Gerratt, J. et al. Theoret. Chim. Acta (1996) 93: 343. doi:10.1007/BF01129215

Abstract

Exact transformations of “N electrons inN orbitals” CASSCF structure spaces are examined that lead to modern valence bond representations, in which the total wavefunction is dominated by covalent structures built from a common product ofnonorthogonal orbitals. The resulting descriptions of the electronic structure may be compared directly with those that arise in the spin-coupled (orfull-GVB) approach. Using singlet methylene, methane and ozone as representative examples, various overlap-based and energy-based criteria are investigated for generating modern VB representations of “N inN” CASSCF wavefunctions, which we denote CASVB.

Key words

CASSCFSpin-coupledVBCASVB

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • Thorstein Thorsteinsson
    • 1
  • David L. Cooper
    • 1
  • Joseph Gerratt
    • 2
  • Peter B. Karadakov
    • 2
  • Mario Raimondi
    • 3
  1. 1.Department of ChemistryUniversity of LiverpoolLiverpoolUK
  2. 2.School of ChemistryUniversity of Bristol, Cantocks CloseBristolUK
  3. 3.Dipartimento di Chimica Fisica ed ElettrochimicaUniversità di MilanoMilanoItaly