Atoms in molecules: Application to electronic structure of van der Waals complexes

Abstract

Systematic investigation has been carried out to calculate critical points, charge density, ρ(rc), and Laplacian of charge density, ▽2ρ(rc), for weak complexes in the framework of MP2 and density functional theory (DFT). This study helps in assigning structures to van der Waals complexes such as Rg-HF, Rg-HCl, Rg-Li+ and Rg-Mg+, where Rg = He, Ne and Ar. The presence of (3, -1) critical points (bond critical points) in the complexes and the typical values of ρ(r) and ▽2ρ(r) at critical points indicate that closed-shell type of interaction is present in the molecules. The possible difference between the two types of bonding, rare gas-hydrogen bond interaction (Rg-H-X) and rare gas-halogen bond interaction (Rg-X-H), (where X = F and Cl) has also been analyzed by computing the properties of charge density and Laplacian of charge density at the bond critical points.