Structural, electronic and magnetic properties of AunPt (n = 1−12) clusters in comparison with corresponding pure Aun+1 (n = 1−12) clusters

Abstract

An all-electron scalar relativistic calculation on Au n Pt (n = 1−12) clusters has been performed by using density functional theory with the generalized gradient approximation at PW91 level. Our results reveal that all the lowest energy geometries of Au n Pt (n = 1−12) clusters may be generated by substituting Pt atom for one gold atom of the Au n+1 cluster at the highest coordinated site. Compared with corresponding pure Au n+1 cluster, the lowest energy geometries of Au n Pt clusters are distorted slightly and still keep the planar structures due to the strong scalar relativistic effect in small gold cluster. The Au-Pt bonds are stronger and most Au-Au bonds far from Pt atom are weaker than the corresponding Au-Au bonds in pure Au n+1 cluster. By substituting Pt atom for one gold atom of Au n+1 cluster at the highest coordinated site, the relatively stable and inactive odd-numbered Au n+1 cluster becomes the relatively unstable and reactive odd-numbered Au n Pt cluster, and the relatively unstable and reactive even-numbered Au n+1 cluster becomes the relatively stable and inactive even-numbered Au n Pt cluster chemically and electronically. All the Au n Pt clusters prefer low spin multiplicity. The even-numbered Au n Pt clusters are found to exhibit zero magnetic moment and the odd-numbered Au n Pt clusters are found to possess magnetic moment with the value of 1 μ B. The odd-even alterations of magnetic moments and electronic configurations for Au n Pt clusters are very obvious and may be simply understood in terms of the electron pairing effect.