POPULATION ANALYSIS OF PAIR DENSITIES - A STUDY OF BASSIS SET DEPENDENCE

Based on work reported by several authors, one of us (RP) has introduc ed a Mulliken-like population analysis of pair densities. This scheme, introduced first at the semi-empirical level, was subsequently genera lised both for SCF and for post-SCF ab initio methods. A potential pro blem is the basis set dependence that can be expected for all kinds of Mulliken-like approaches. The main purpose of the present study is to quantify this basis set dependence for a range of simple molecules, u sing basis sets ranging from STO-3G to TZVP quality. It is shown, exce pt for low quality basis sets, that the >>effective<< pair populations derived from ab initio SCF calculations are relatively insensitive to the choice of basis set.