Dipole moment surface of the van der Waals complex CH4-N2

The interaction-induced dipole moment surface of the van der Waals CH4-N-2 complex has been calculated for a broad range of intermolecular separations R and configurations in the approximation of the rigid interacting molecules at the MP2 and CCSD(T) levels of theory using the correlation-consistent aug-cc-pVTZ basis set with the basis set superposition error correction. The simple model to account for the exchange effects in the range of small overlap of the electron shells of interacting molecules and the induction and dispersion interactions for large R has been suggested. This model allows describing the dipole moment of van der Waals complexes in analytical form both for large R, where induction and dispersion have the key role, and for smaller R including whole ranges of their potential wells, where the exchange effects are important. The proposed model was tested on a number of configurations of the CH4-N-2 complex and was applied for the analytical description of the dipole moment surface for the family of the most stable configurations of the CH4-N-2 complex. (C) 2010 American Institute of Physics. [doi:10.1063/1.3494539]