Potential energy surfaces, calculation generalized valence bond

Of the methods which have been developed in recent years to calculate the potential energy surfaces of molecular systems, we have found the generalized valence bond (GVB) and derived configuration-interaction (CI) methods to be most useful. The GVB wavefunction provides a consistent theoretical description of molecules and their fragments and, as such, is well suited for studying the reactions of atoms and molecules. In addition, the GVB wavefunction is an orbital wavefunction this allows the features of the potential energy surfaces to be correlated with changes in the orbital structure of the system. 

Warshel and collaborators (Warshel and Sussman, 1986 Warshel et al., 1988) developed the empirical valence bond method for obtaining free-energy differences and activation free energies. The effects of Gly-to-Ala mutations in trypsin were accurately simulated. This method was earlier applied to calculation of the potential surface for general acid catalysis of a disaccharide in solution and bound to lysozyme (Warshel and Weiss, 1980). 

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