Stability and Ionization-Induced Structural Transitions of Sodium Chloride Microclusters from Hartree-Fock Calculations: Na sub 2 Cl sub 2 Sup((+)) And Na sub 2 Cl sup((+))

摘要

The equilibrium properties of (NaCl) sub 2 and Na sub 2 Cl in both the neutral and the singly ionized state are evaluated by the Hartree-Fock method in a pseudopotential approach. Specific attention is given to ionization processes, in relation to observations on the relative abundance of Na/sub n/Cl sup + /sub n-1/ and Na/sub n/Cl sup + /sub n/ clusters in mass spectra. Ionization is shown to be followed in both systems by symmetry breaking, leading to an equilibrium linear structure for Na sub 2 Cl sup + and to a triangular shape for the ionized dimer. The latter is very weakly bound against dissociation into Na sub 2 Cl sup + and a chlorine atom. These results provide a natural explanation for mass spectroscopy data on clusters, showing that chlorine-deficient ionized aggregates are more frequently observed than stoichiometric ones, and are also in broad agreement with experimental data on dissociation energies, ionization potentials and equilibrium structural parameters. 17 refs, 10 figs, 2 tabs. (Atomindex citation 17:066107)