THE INTERMOLECULAR POTENTIAL-ENERGY SURFACE FOR CO2-AR - FITTING TO HIGH-RESOLUTION SPECTROSCOPY OF VAN-DER-WAALS COMPLEXES AND 2ND VIRIAL-COEFFICIENTS

Two potential energy surfaces for CO2-Ar are obtained by least-squares fitting to the high-resolution spectra of Van der Waals complexes and the second virial coefficients of Ar+CO2 mixtures, The potentials inc orporate a repulsive wall based on monomer ab initio calculations and the assumption that the repulsion potential is proportional to the ove rlap of the monomer charge densities. The dispersion energy is represe nted in a two-site model, with dispersion centers located along the C- O bonds of CO2. The-resulting potentials give a good representation of all the experimental data with only three or four adjustable paramete rs. They are quite different from previous empirical CO2-Ar potentials , which all have either a poor representation of the attractive well o r a poor representation of the repulsive wall. (C) 1996 American Insti tute of Physics.