Theoretical Study of Structural and Vibrational Properties of (AlP)n, (AlAs)n, (GaP)n, (GaAs)n, (InP)n, and (InAs)n Clusters with n = 1, 2, 3

The structure, geometry, and vibrational frequencies of several isomers of small group III−V (MX) n clusters ( n = 1, 2, 3; M = Al, Ga, In; X = P, As) have been investigated using density functional theory. The results reveal the same behavior as in the nitride clusters for monomers and dimers. The Al trimers exhibit a D 3 h structure like the nitride, but the gallium and indium trimers exhibit a three-dimensional structure of C s symmetry. The existence of strong X−X bonds dominates both the structure and the vibrations of the Ga and In trimers.