Competitive shell-filling in protonated helium clusters Original Research Article

The stability steps during the growth of small helium clusters containing a proton charge are examined by performing energy optimization calculations that use a density-functional-based interaction potential. The results obtained for [HenH]+ cluster with n between 5 and 9 are further analysed by carrying out simulated “temperature” annealing dynamics. They clearly reveal that the first helium shell outside the (He2H)+ ionic moiety is preferentially filled by up to four atoms before the next layer starts being populated and that, when five equatorial atoms are directly bound to the He+ impurity, the latter clusters are found to be markedly less stable than the former ones.