Abstract
Three-body contributions to the van der Waals interaction potentials for the ground states of Ne3 and Ar3 are evaluated within the matrix Hartree-Fock model (self-consistent-field within a finite basis set). The calculations are performed for the nuclear geometries which occur as nearest neighbour triangles in solid neon and solid argon, enabling an estimate to be made of the matrix Hartree-Fock contribution to the three-body lattice energy of these solids.