The calculation of molecular response properties using perturbed spin-coupled wave functions. II. Polarizability and magnetic susceptibility of H2 and LiH as functions of internuclear distance

The perturbed spin-coupled formalism of the previous paper is applied to the calculation of the polarizabilities and magnetic susceptibilities of H2 and LiH. These are the first applications of the theory and as such much attention is paid to the choice of basis set, particularly as a function of internuclear distance. For H2, the results can be compared with the accurate calculations of Rychlewski [Mol. Phys. 41, 833 (1980)] and of Rychlewski and Raynes [Mol. Phys. 41, 843 (1980)]. The agreement with these is good, provided that the basis set is adequate. For LiH, there has, to our knowledge, not been any calculation of these properties as a function of R. However the value of α at large R is in excellent agreement with the value of α(Li)+α(H). A remarkable feature in LiH is that the value of αzz at ∼7a0 is ten times that for R=Re. In general we find that the determination of magnetic susceptibilities as a function of R forms a very severe test of the completeness of the basis set.