Development of isotropic site–site potential for exchange repulsion energy based on ab initio calculation. I. Closed shell system

We developed isotropic site–site potential for exchange repulsion energy based on ab initio calculation. This work has two important points. One is that the introduced parameters can be determined from the electronic structure of a single molecule but not supermolecule. Another one is that we can employ the obtained potential directly in integral equation theory by using lookup-table approach. In this work, the present method was applied to simple examples (H2O, NH3, CH4, Cl−, and Na+) and metal complexes Zn(Me)2 and Zn(OH)2. The obtained potentials reasonably reproduced those obtained by Kitaura–Morokuma analysis and effective fragment potential.