Alkali and alkali-earth ions inHe4systems

Abstract

We study with variational Monte Carlo simulations a single ion impurity in nanodroplets and in liquid $^{4}\mathrm{He}$. Within the shadow wave function (SWF) approach we have studied alkali-earth ion doped $^{4}\mathrm{He}$ systems (${\mathrm{Be}}^{+}$ and ${\mathrm{Mg}}^{+}$) and we have also improved our previous variational results for alkali ion impurities (${\mathrm{Na}}^{+}$, ${\mathrm{K}}^{+}$, and ${\mathrm{Cs}}^{+}$). The new $\mathrm{SWF}$ allows for anisotropic correlations between $^{4}\mathrm{He}$ atoms and the ion. The first shell of $^{4}\mathrm{He}$ 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 $^{4}\mathrm{He}$ 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.