Ab initio MP2 study of the HF ... ClF complex using various extended basis sets and bond functions

Abstract

The stationary points on the intermolecular potential energy surface (PES) for the HF ... ClF complex have been investigated at the second-order Moller-Plesset perturbation theory (MP2) level using various extended bais sets, including diffuse functions, and also bond functions. The last ones were placed at different intermolecular positions, for distinct stationary points. The basis set superposition errors (BSSE) were accounted for using the counterpoise method. Besides the anti-H-bonded and H-bonded minimum energy structures, four transition state structures were also located on the PES. It was shown that higher polarization functions are required for the description of the anti H-bonded isomer and diffuse functions had to be included for the H-bonded isomer. The bond functions are able to replace thef (Cl, F) andd(H) polarization functions at a lower computational cost. However, for the H-bonded isomer intramolecular electron correlation also plays an important role. So we have to use diffuse nucleus centered polarization functions for an adequate description of intermolecular and intramolecular correlation.