Phillips et al. 1994
Phillips, T.R., S. Maluendes, A.D. McLean, and, 1994: Anisotropic rigid rotor potential energy function for H2O-H2. J. Chem. Phys., 101, 5824-5830, doi:10.1063/1.467297.
We have calculated the interaction for H2O-H2 at 722 points on a five-dimensional surface where both molecules are treated as rigid rotators, and we have fitted the ab initio points to a 48-term angular expansion of products of spherical harmonics and rotation matrices. The resulting potential energy function shows strong angle dependence with a large contribution from electrostatic interactions. When averaged over H2 orientations, the resulting water-atom-like surface is found to have zero-crossing and minimum at similar distances to the corresponding H2O-He surface but to be generally more repulsive at short range and more attractive at long range. The isotropic average of the potential has a zero-crossing radius σ = 3.05 and a well depth g = 49.5 /cm at an intermolecular separation Rm = 3.52.