Theoretical Evaluation of Radii of Atoms in Molecules and their Dependence on Atomic Partial Charge

Quantification of radii of atoms in molecules is of fundamental importance in understanding a wide range of physical and chemical phenomena. In the present study, we develop methods for evaluation of radii of atoms in molecules and assess their robustness by studying the agreement of van der Waals and solvent excluded surfaces constructed by them with reference iso-density surfaces. By studying a large dataset of 1235 molecules, we show that estimation of atomic radii via effective and free atomic volumes can accurately take the dependence of atomic radii on the chemical environment into account. A linear dependence of atomic radii on partial charge is found for radii estimated via effective volumes and partial charges computed based on iterative Hirshfeld and MBIS partitioning methods.