Alkali-metal ion in rare gas clusters: global minima
  Structural optimization for heteronuclear clusters consisting of one alkali-metal ion and of up to 79 neutral rare gas atoms has been carried out. The basin-hopping Monte Carlo minimization method of Wales and Doye is used. Rare gas atoms interact with the Lennard-Jones potential, whereas the interaction between a neutral atom and an ion impurity is given by the Mason-Schamp potential. Starting from eight rare gas atoms the alkali-metal ion is always inside a cluster. 
G. Bilalbegovic