A method for calculating the electrostatic energy between small polar molecules. The multipole-fitted point-charge method

Abstract

A comparison is made between the one-centre multipole expansion and point-charge models of the electrostatic interaction energy for the dimers of HF, HCl and H₂O. Comparison with the exact electrostatic energy shows that the point-charge models are more accurate for equivalent levels of computational difficulty. For H₂O a comparison is made between three-charge and four-charge models and the four-charge models show no significant improvement over the best three-charge model. Optimum parameters based on experimental and computed moments are given for this three-charge model.