Anisotropy of correlation effects in hydrogen-bonded systems: the HF dimer

Abstract

Correlation corrections to the interaction energy of the (HF) 2 complex are evaluated within a supermolecules Møller-Plesset treatment as well as by the intermolecular perturbation theory approach. The correlation correction to the electrostatic effect is the most orientation-dependent contribution. The anisotropy of the dispersion energy is less pronounced and can be easily interpreted and predicted by considering the overlap of the occupied subsystems' orbitals. The validity of the Hartree-Fock plus dispersion (HF+D) potential in modeling H-bonded systems is discussed.