Second-order calculations with the DDSI

The effective density-dependent Sussex interaction and the Coulomb interaction are used in second-order nuclear closed-shell calculations. In particular, mixed second-order graphs, not accounted for to lowest order with this effective interaction, are evaluated. The calculations of the first- and second-order energies and root-mean-square radius are performed using a harmonic oscillator basis for a realistic range of the size parameter for both 16O and 40Ca, including excitations up to 4(h/2π)ω and states up to 2p-2h. Five such effective density-dependent interactions are used, and the sensitivity of the results to the power of the density is studied. (author)