Structure and stability of Xe+n 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).