Bond dependence of dipole polarisabilities in HF and HCl molecules

Ab initio calculations, within a perturbation treatment of the coupled Hartree-Fock equations are reported for the static dipole polarisability components of polar diatomics. Their dependence on internuclear-separation values around the molecule equilibrium positions is also computed and discussed. The relevance of the present results for vibrationally inelastic collisions of slow electrons pointed out in its relation with previous empirical estimates of the polarisability first derivatives.