Energy decomposition scheme for combined ab initio quantum mechanical/molecular mechanical methods

摘要

A new energy decomposition scheme is presented which paves the way toward the accurate and simple treatment of boundary atoms in combined ab initio quantum mechanical / molecular mechanical methods. We extend the wave function beyond the quantum region to a few atoms of the molecular mechanical region, which are linked directly to boundary atoms. Furthermore, we apply an approximate decomposition scheme, which allows calculating the total energy in terms of one-center atomic contributions. Comparisons with reference ab initio calculations are made, and good agreement is obtained for geometry parameters referring to C-C, C=C, and C-X (X=O, S, N) bonds at the boundary, as well as for the rotational energy curve of n-butane. (c) 2005 Wiley Periodicals, Inc.