Calculation of spectra and spin-spin coupling constants using a coupled-cluster polarization propagator method

We present a coupled-cluster polarization propagator method based on a coupled cluster singles and doubles reference state. Applications to the Be atom show that we may calculate electronic excitation energies with an average absolute error of about 0.08 eV using this method. We have also calculated the nuclear spin–spin coupling constant of 1H19F to be 524.4 cps, in good agreement with experiment. For Be there is a large effect of using coupled-cluster rather than a low-order Rayleigh–Schrödinger expansion, whereas the coupling constant of HF is less sensitive to this improvement in the reference state.