Inclusion of the quadrupole moment when describing polarization. The effect of the dipole-quadrupole polarizability.
A method to compute distributed dipole-quadrupole polarizabilities is suggested. The method is based on numerical differentiation of distributed quadrupole moments, using finite field perturbation calculations. It is tested using two different multicenter multipole expansions, and compared with results using polarizabilities obtained via the uncoupled Hartree-Fock approximation. The accuracy of th
