Molecular charge density analysis

Abstract

It is proposed to analyse the first-order reduced density matrix of a molecular wave function in terms of the first-order reduced density matrices of different states of the constituent atoms. With this an unambiguous partitioning of the molecular charge distribution in terms of the atomic charge distributions is obtained. Simple practical formulae are derived, such that in many ab initio molecular wave function calculations the analysis proposed can be carried out routinely. The results obtained should be useful for the interpretation of molecular wave functions in terms of their atomic constituents, as well as for the determination of atomic form factors to be used in X-ray molecular structure determination. Some simple examples are given, and the results obtained are compared with those obtained using other methods of analysis. Key words: charge density, density matrix, goodness-of-fit, correlation coefficient, standard deviation.