Electric polarizability of some diatomic molecules

A variation-perturbation method is employed for the calculation of the electric polarizability tensor of a series of diatomic molecules (H2, Li2, N2, LiH, HF, LiF, CO). The SCF-LCAO-MO functions of Ransil are used as unperturbed solutions and appropriately orthogonalized perturbation functions are introduced to account for the effect of the electric field. For the three molecules (H2, N2, CO) for which experimental data are available, reasonable agreement between the theoretical and the measured values is obtained. However, the calculations appear to somewhat overestimate the electric polarizability, particularly so for the parallel component of the tensor; possible theoretical refinements to reduce this error are discussed.