Abstract

The availability of quantum mechanical wave functions in molecular dynamics simulations - for example in those of the Car-Parrinello type - offers the ability to analyze intermolecular interactions of a system in terms of quantum chemical descriptors. We demonstrate how standard population analyses can be utilized for a semiquantitative analysis of intermolecular interactions. The approach is therefore of particular value for the study of those systems for which geometric criteria and predefined interaction potentials have not yet been obtained. This is demonstrated for a DMSO-water mixture, for which the population-analysis criterion provides a simple measure for different interaction types, e.g., between water-oxygen and methyl-hydrogen atoms. In the case of a polypeptide, it is shown that the wave-function-based criterion provides insight into hydrogen bonding of the C=O groups with a hydrogen atom attached to a carbon atom from the peptide's backbone.