The theory of analyzing molecular energies, as found fromabinitiocomputations, in terms of the contributions from specific sets of atoms or centers is discussed. It is shown that the basishyphen;function expansion of molecular wave functions in general leads to energetic interactions involving only onehyphen; through fourhyphen;center terms. For the special case of selfhyphen;consistenthyphen;field energies the formulas for the energy terms are given explicitly and several numerical properties are presented, including basishyphen;set dependence, the differences between terms that arise in chemical reactions, and the first and second derivatives of individual terms with respect to molecular deformations. Expressions are also given for the multicenter resolution of correlation energies employing secondhyphen;order manyhyphen;body perturbation theory. Some numerical examples of the latter are also presented.
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