One-electron pseudopotential study of NanFn-1 clusters (2 <= n <= 29). I. Electronic and structural properties of the ground state

We introduce a one-electron pseudopotential model to study the structural a nd electronic properties of excess-electron alkali halide clusters. This mo del assumes total charge transfer between alkali and halide atoms. This ion ic part of the system is described via repulsive and Coulomb potentials. Th e remaining electrons of the excess metal atoms are treated within an expli cit quantal scheme via ion-electron pseudopotentials. Moreover, explicit co re-polarization and core-electron correlation contributions are taken into account. This model is used to derive ground state structural, energetics, and electronic properties of one-excess electron NanFn-1 clusters in the ra nge 2 less than or equal to n less than or equal to 29. We show that the st ructural characters are closely related with electron localization and we p ropose a classification into five types, two of them exhibiting rather stro ng localization namely F-centers and Na-tail structures, the others exhibit ing a less bound electron localizing in a surface-state, an edge-state, or on an atom-depleted face of the cluster. Although we observe an energetical predominance of cubiclike structures, hexagonal isomers are seen to appear as stable ones and exhibit similar localization features. The various ener gy contributions to the stability are examined. All studied NanFn-1 cluster s are found stable with respect to fragmentation. The ionization potentials , which are seen to reflect faithfully the localization character, are disc ussed in details and compared with consistent recent experimental data. (C) 1999 American Institute of Physics. [S0021- 9606(99)00715-1].