Electronic structure of small GaAs clusters. II

摘要

The electronic and geometrical structures of GaxAsy(x+y= 3ndash;10) clusters in nonstoichiometric (xne;y) compositions have been calculated using the localhyphen;spinhyphen;density method. The results show that all evenhyphen;numbered GaxAsy(x+y= even) clusters have closed shell electronic structures. The calculated ionization potential and electron affinity for the evenhyphen;numbered clusters are distinctively different from the neighboring oddhyphen;numbered clusters, forming an even/odd alternating pattern with increasing cluster size. This calculation, combined with the results from an earlier calculation for stoichiometric compositions (x=y), shows that the electronic ground states of evenhyphen;numbered gallium arsenide clusters in the size range 4ndash;10 atoms are closedhyphen;shell singlet states with a substantial highest occupied molecular orbitalndash;lowest unoccupied molecular orbital (HOMOndash;LUMO) gap.