Characterization of van der Waals interaction potentials D-4h and T-d configurations of He-4

Van der Waals interaction potentials of the square planar D-4h and regular tetrahedral T-d configurations of He-4 were examined at the matrix Hartree-Fock, many-body perturbation theory, coupled-cluster theory, and configuration interaction levels of ab initio theory. Potential energy minima, pairwise and nonpairwise additivity, group theoretical parameters, and isotope substitution effects were found to uniquely characterize these interactions. (C) 2000 John Wiley \& Sons, Inc.