Interaction potential for He/H2 including the region of the van der waals minimum

The energy of He/H₂ in its ground state is calculated in an ab-initio way using the IEPA PNO method for three different H-H distances, three different angles and for distances between He and the midpoint of H₂ ranging from 3 to 20a₀.A van der Waals minimum of ≈21°K is found for the linear arrangement and a saddle point of ≈14°K for the C_2v geometry. The computed hypersurface is compared with experiment and with the R^?6 term known from perturbation theory. The anisotropy of the potential is much larger than what is predicted asymptotically.