Dynamic polarizabilities of open-shell systems by coupled Hartree-Fock perturbation theory

A computational scheme for frequency-dependent polarizabilities of open-shell systems by coupled Hartree-Fock perturbation theory is presented. It allows the simultaneous approximate prediction of the involved electronic transition energies and can trivially be extended to imaginary values of the frequency. As a simple application, the dipole polarizability and some related properties of Li atoms are evaluated, the agreement with previous estimates being excellent.