Flexible multipole models for hydrogen fluoride
Abstract
We
use the distributed multipole analysis method to analyse the charge density of the hydrogen fluoride molecule,
including variation of the HF bond length, and taking into consideration the level of theory, the basis
set, and the number of sites used. We also examine the effects of truncating the dimer electrostatic interactions at charge–charge, quadrupole–quadrupole and all interactions up to r−5 dependence in the intermolecular
site–site separations. We assess the accuracy of these approximations using both the calculated multipoles
and multipoles described by polynomial functions of the bond stretching coordinate. We consider two ranges
of the HF bond length, one of which should be suitable for calculations of structures and energetics of