Reintroduction of ionic structure in the self-consistent jellium model for metal clusters: Pseudopotential perturbation theory

The structureless self-consistent jellium model for simple metal clusters is corrected by reintroducing the ionic structure via second-order pseudopotential perturbation theory. It is found that this formulation is enough to bring this approximate treatment into a quantitative agreement with fully fledged ab initio Car-Parrinello structure optimization. Furthermore, the ionic perturbation leads to a substantial improvement in the description of the optical response.