32.11.2 Printing weights of the valence bond structures

For further details regarding the calculation of weights in CASVB, see T. Thorsteinsson and D. L. Cooper, J. Math. Chem. 23, 105-26 (1998).

VBWEIGHTS,key1,key2,...

Calculates and outputs weights of the structures in the valence bond wavefunction $\Psi_{VB}$. key specifies the definition of nonorthogonal weights to be used, and can be one of:

CHIRGWIN

Evaluates Chirgwin-Coulson weights (see: B. H. Chirgwin and C. A. Coulson, Proc. Roy. Soc. Lond. A201, 196 (1950)).

LOWDIN

Performs a symmetric orthogonalization of the structures and outputs the corresponding weights.

INVERSE

Outputs ``inverse overlap populations" as in G. A. Gallup and J. M. Norbeck, Chem. Phys. Lett. 21, 495-500 (1973).

ALL

All of the above.

NONE

Suspends calculation of structure weights.

The commands LOWDIN and INVERSE require the overlap matrix between valence bond structures, and some computational overhead is thus involved.