The interaction between He and H2+:: anisotropy, bond length dependence and hydrogen bonding

An extensive high level ab initio study of the ground electronic state of HeH2+ has been used to generate an improved intermolecular potential for He + H-2(+) that includes a more complete account of the long range forces, the short range anisotropy, and the dependence of the potential on H-2(+) bond length r. In good agreement with earlier work, the potential is found to have a minimum for collinear geometry, with a well 7.799 kcal mol (2728 cm-l) deep with respect to separated He + H-2(+)(r = r(e) = 1.9982 a(0)) at an intermolecular distance R = 2.963 a(0)(1.568(4) Angstrom) and a bond length r = 2.074(2) a(0) (1.098 Angstrom).