Origin of attraction and directionality of hydrogen bond and halogen bond: Analysis by ab initio MO calculations

Abstract

The origin of the directionality of hydrogen bond and halogen bond was studied by ab initio molecular orbital calculations and by analysis of the electrostatic energy using distributed multipoles. The calculations clearly show that the electrostatic interaction is mainly responsible for the directionality of hydrogen bond and halogen bond, although the orbital-orbital interaction was often claimed as the cause of the directionality.