A new ab initio based six-dimensional semi-empirical pair interaction potential for HF

We present an analytical pair potential for hydrogen fluoride based on 3284 ab initio points at counterpoise-corrected MP2-R12 and lower levels using a large basis set. Empirical refinements are applied through comparison of experimental data with solutions of the multidimensional nuclear Schrodinger equation and appropriate mixing and scaling of the ab initio data. The new potentials are compared to previous dimer potential hypersurfaces and spectroscopic data, yielding best estimates of 19.1(2) kJ/mol for the dimer dissociation energy D-e and 4.2(2) kJ/mol for the electronic hydrogen bond tunneling barrier.