An extension of the time-dependent Hartree-Fock approximation to employ a multiconfiguration Hartree-Fock state as reference state has been developed. Preliminary multiconfiguration time-dependent Hartree-Fock calculations with the ground state of the Be atom using the configurations 2s2 and 2p2 show a maximum deviation from the experimental excitation energies of 0.31 eV for the lowest 16 excitations, with an average deviation of 0.18 eV. 1979.
