Potential energy surfaces in hybrid quantum mechanical/molecular mechanical methods

The problem of conjunction between quantum and classical parts in hybrid qu antum mechanical/molecular mechanical methods is considered. The form of th e junction is deduced with use of the perturbation expansion on the assumpt ion that the wave function underlying molecular mechanics is of the antisym metrized product of strictly localized geminals type. The renormalization o f the potential energy surfaces of the combined system due to interaction b etween quantum and classical subsystems is represented as a sum of contribu tions with transparent physical sense. (C) 2001 John Wiley & Sons, Inc.