Structure and stability of Xe+<i>n</i> clusters

Abstract

The equilibrium structure and energy of Xe+n clusters (n≤9, n=13 and 19) have been calculated using a model (of excitonic type) hamiltonian extracted from the potential curves of Xe+2 and Xe2, and including spin–orbit coupling and three-body interactions between instantaneous induced dipoles. Due to the p nature of the valence AO, the hole delocalization proceeds along one direction but it rapidly becomes less favorable to delocalize the hole on an nth atom than to polarize a neutral atom situated around the (n−1) atoms linear cluster. Xe+3 and Xe+4 are therefore linear and generate two families of heavier clusters, obtained by polarizing neutral atoms situated on crowns around the axis of the Xe+3 or Xe+4 ionized cores. Each crown may bear up to five atoms and there are two crowns around Xe+3, three crowns around Xe+4, Xe+13, and Xe+19 appearing then as compact structures with filled crowns. Rules are given for the filling of the neutral crowns. The two families (Xe+3 supported and Xe+4 supported) are nearly degenerate in energies with numerous isomers. The calculated adiabatic ionization potential for Xe19 (10.1 eV) is in good agreement with the observed value for the bulk (9.8 eV).