Bimetallic Clusters Pt6Au: Geometric and Electronic Structures within Density Functional Theory.

Abstract

Within density functional theory at the general gradient approximation for exchange and correlation (BPW91) and the relativistic 19-electron Los Alamos National Laboratory effective core pseudopotentials and basis sets (3s3p2d), the geometric and electronic structures of Pt6Au bimetallic clusters have been studied in detail in comparison with Pt7. A total of 38 conformations for Pt6Au are located. The most stable conformation for Pt6Au is a sextet with an edge- and face-capped trigonal bipyramid, in which the Au atom caps an edge of the trigonal bipyramid. Pt6Au, in general, prefers a three-dimensional geometry and high spin electronic state with multireference character. The electronic impact of the doping of Au in Pt clusters on the overall chemical activity of the doped bimetallic cluster is not as significant as that of the doping of Pt in Au clusters; however, the doping of Au lowers the chemical activity, thus enhancing the chemoselectivity in the gas phase, of PtAu bimetallic clusters.