An intermolecular perturbation approach to hydrogen bondings in systems in the ground and excited electronic states

Abstract

The intermolecular interaction energy for binary systems in the ground and excited electronic states was partitioned into the Coulomb, exchange-repulsion, induction, dispersion and charge-transfer interaction terms by the perturbation expansion method. The various interaction terms were evaluated for the hydrogen bondings in (HF)2, (H2O)2, (CH3OH)2, (RCOOH)2, and HF·H2O in various geometrical configurations. It has been found that the Coulombic interaction plays a dominant role in the stability of these hydrogen bonded systems. The method was further applied to the HCOOH·H2O codimer in both the ground and excited singlet electronic states. The results were in accord with the well-known water solvent effects on the shifts of absorption spectral bands.