Alkali and alkali-earth ions in 4He systems

We study with variational Monte Carlo simulations a single ion impurity in nanodroplets and in liquid He-4. Within the shadow wave function (SWF) approach we have studied alkali-earth ion doped He-4 systems (Be+ and Mg+) and we have also improved our previous variational results for alkali ion impurities (Na+, K+, and Cs+). The new SWF allows for anisotropic correlations between He-4 atoms and the ion. The first shell of He-4 atoms around the ions has always a well defined solidlike structure, which is remarkably different for each ion but it does not depend on the He-4 system (bulk liquid or cluster). We also give results for the chemical potential, the single particle excitation spectrum, and the effective mass of the ions in the bulk.