Symmetry adaptation and the utilization of point group symmetry in valence bond calculations, including CASVB

Abstract

We present practical approaches for symmetry-adapting valence bond wave functions, with emphasis on the CASVB method. Significant savings in the computational effort become available, both in relation to the application of the Hamiltonian operator and to the reduced number of variational parameters. Results are presented for modern VB representations of CASSCF descriptions of benzene and diborane.