Structure, stability, dipole polarizability and differential polarizability in small gallium arsenide clusters from all-electron ab initio and density-functional-theory calculations (original) (raw)

We have employed conventional ab initio and density-functional-theory ͑DFT͒ methods to study the structure, stability and electric polarizability of small gallium arsenide clusters Ga n As n . We relied on purposeoriented, carefully optimized basis sets of Gaussian-type functions. We have calculated both the mean dipole polarizability ͑␣ ͒ and the anisotropy ͑⌬␣͒. Our results show that the differential-per-atom polarizability of the most stable isomers decreases rapidly with cluster size. Compared to the ab initio results, the widely used Becke's three-parameter exchange DFT functional with the Lee, Yang, and Parr correlation functional and Becke's three-parameter exchange DFT functional with Perdew and Wang's 1991 gradient-corrected correlation functional density-functional-theory methods follow clearly the trend of the differential-per-atom polarizability ␣ diff / atom for the most stable isomers and predict values closer to the self-consistent field method but distinctly lower than second-order Møller-Plesset perturbation theory. All methods predict a positive value for the dimer, ␣ diff / atom ͑Ga 2 As 2 ͒ Ͼ 0.