THE STRUCTURES AND STABILITIES OF HELIUM CLUSTER IONS

Previously published 2-body and 3-body terms for an n-valued represent ation of the potential functions of He-n(+) have been used to examine the structures of larger clusters. For n = 3-8 the most stable structu re has a linear He-3(+) core surrounded by weakly bound, nearly neutra l atoms, with up to four lying in an equatorial plane. Such structures persist as metastable species up to n = 12. For n > 8 the most stable structure consists of a He-2(+) core with up to nine atoms closely at tached. The first excited state is predicted to have a vertical excita tion energy of between 5.5 eV and 5.9 eV, changing little with n. This is in broad agreement with experimental observations.