On the doping of the Ga12As12 cluster with groups p and d atomic impurities

We report a theoretical study of how the physical and chemical properties of the Ga12As12 cluster change upon doping with atomic impurities of groups p and d. Calculations were performed within the density functional theory with the generalized gradient approximation to the exchange and correlation energy functional. We consider the Ga11As12X and Ga12As11X doped clusters, where X is an atomic impurity (from B-P, Al-Cl, Cr-Cu and Mo-Ag in their respective series) that substitutes either a Ga or an As atom at. We found that, in general, the substitution of a Ga atom is a more exothermic process than the substitution of an As one, in accordance with experimental reports on doped GaAs bulk. Some of the transition metal dopants (Cr, Mn, Fe, Mo and Tc) interact in such a way that the magnetic moment of the clusters is enhanced. We discuss the doping effect by analyzing the structural changes, binding energies per atom, HOMO-LUMO gaps, and relevant vertical chemical descriptors.