ABINITIO THEORETICAL-STUDY OF SMALL GAAS CLUSTERS

Theoretical calculations for the closed-shell ground state of small GaxAsy (x = y; x = 2-4) are carried out at the self-consistent field (SCF) Hartree-Fock level of theory, using analytic energy gradients for rapid geometry optimization. In addition, for Ga2As2, the SCF results are compared with theoretical predictions obtained at the coupled cluster level of theory including all single, double and perturbative triple excitations, CCSD(T). The equilibrium structures for Ga2As2, Ga3As3, and Ga4As4 are found to be of D2h, C(l), and C(i) symmetry, respectively. The cluster binding energies with respect to GaAs dimers (3-SIGMA-) and Ga(2P) + As(4S) atoms are also obtained.