ON THE ELECTRONIC-STRUCTURES OF GAAS CLUSTERS

Ah initio molecular orbital theory is used to investigate the electron ic and geometric structures of Ga(x)As(y) (x = y, 1 less-than-or-equal -to x less-than-or-equal-to 4) clusters. Correlation calculations are performed at the fourth-order many-body perturbation theory level. The ground state structure of Ga2As2 is found to be a rhombus, of Ga3As3, a Ga-capped trigonal bipyramid and, of Ga4As4, a rhombic prism. Elect ronic states, binding energies, ionization potentials and electron aff inities of the clusters are presented and, wherever possible, compared with other published data in the literature. Mulliken population anal ysis indicates that the bonding in GaAs clusters is of a mixed type.