ON THE EFFECTIVENESS OF MONOMER-CENTERED, DIMER-CENTERED, AND BOND-CENTERED BASIS FUNCTIONS IN CALCULATIONS OF INTERMOLECULAR INTERACTION ENERGIES

A range of basis sets differing in the location of basis functions has been explored from the point of view of the effectiveness of calculating the electrostatic, induction, dispersion, and exchange components of intermolecular interaction energies. Possible location strategies range from monomer-centered basis sets, through the dimer-centered ones, to sets with functions centered at the intermolecular bond. It is shown that the most effective approach is to use the so-called ''monomer plus'' basis sets containing, in addition to monomer-centered functions and bond functions, a small number of functions centered on the interacting partner. Using such basis sets for He-2 and (H2O)(2) the best values to date have been obtained for several interaction energy components. The conclusions from this work are relevant also for supermolecular calculations of interaction energies. (C) 1995 American Institute of Physics.