Basis set effects on the intermolecular interaction of hydrocarbon molecules obtained by an ab initio molecular orbital method: evaluation of dispersion energy

Abstract

The intermolecular interaction potentials of methane, ethane, ethylene and benzene dimers were calculated using several basis sets [up to 6–311G(3d,4p)] with electron correlation correction by the Møller-Plesset perturbation method and basis set superposition error (BSSE) correction. The calculated interaction energies considerably depend on the basis set used. Whereas the interaction energies of the repulsive and Coulombic energy components calculated at the HF level are not affected by the change of the basis set, the dispersion energy component, calculated as the electron correlation energy, greatly depends on the basis set used. A basis set with multiple polarized functions is necessary to calculate the dispersion energy correctly. The use of small basis sets greatly underestimates the dispersion energy.