Electronic and geometric structure ofAuxCuyclusters studied by density functional theory

We have determined the stable structures ofAuCun,Au2Cun,Au3CunandAuxCu8-xclusters. It has been observed thatAuCun,Au2CunandAu3Cunsystems have two-dimensional (2D) structures up to six atoms and they become three-dimensional (3D) afterwards.AuxCu8-xclusters favor 3D structures till theAu7Cu1cluster. We have found a lowest energy isomer ofAu6Cu2from the literature. Bond lengths, binding energies, density of states (DOS), highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) gaps, ionization potential (IP) and electron affinity (EA) have been calculated for these structures using the first principles density functional theory (DFT) within the generalized gradient approximation (GGA) and the local density approximation (LDA). Generally, we have observed the overlap between s electrons ofCuand p electrons ofAunear the Fermi level. Charge transfers are calculated by using the Löwdin analysis. It is observed that oneCuatom does not significantly modify the clusters which have more gold atoms. It is also seen that these clusters generally have nonmagnetic properties and results are consistent with the hybridization between s and d orbitals ofAuinAuxCu8-xclusters.