Metallization of the Na 14 Cl 13 Cluster

The structure and energetics of multiple-excess-electron alkali halide clusters Na 14 Cl 14- n , (1 ⩽ n ⩽ 6) is studied by ab initio calculations using norm-conserving pseudopotentials and local-spin-density-functional theory. Analysis of various electronic properties (Kohn-Sham one-electron eigenvalue spectra, ionization potentials, participation ratios of Kohn-Sham orbitals), as well as multiple F -center formation energies, suggests that these clusters can be characterized as Na n (NaCl) 14- n having a "phase-separated" metallic part Na I . The Na 14 Cl 9 (or Na 14 Cl 9 + ) cluster exhibits a face (surface) segregated metallic Na 5 (Na 5 + ) overlayer, the stability of which is demonstrated by a molecular-dynamics simulation at 660 K.