Role of Ag-doping in small transition metal clusters from first-principles simulations

Abstract

First-principles calculations are used to systematically investigate the geometric and electronic structures of both pure TMn(n=2-4) and Ag-modulated AgTMn-1(n=2-4; 3d -transition metal (TM): from Sc to Cu; 4d -TM: from Y to Ag elements) clusters. Some new ground state structures are found for the pure TMnclusters, such as a low symmetry configuration for Cr3, which is found to be about 0.20 eV more stable than the previously reported C2vsymmetry. In the most cases, Ag-doping can significantly elongate the bond lengths of the clusters and induce geometric distortions of the small clusters from the high dimensional to the low dimensional configurations. Importantly, introduction of Ag significantly changes the electronic structures of the small clusters and modulates the density of states in the proximity of the Fermi levels, which also varies with the size and the type of the cluster. The results contribute to future design of effective bimetallic alloy Ag/TM catalysts. © 2009 American Institute of Physics.