Structural, electronic and magnetic properties of AunPt (n = 1−12) clusters in comparison with corresponding pure Aun+1 (n = 1−12) clusters
College of Physics, Chongqing University,
2 School of Science, Southwest University of Science and Technology, Mianyang, Sichuan 621010, P.R. China
Received in final form: 11 March 2011
Published online: 17 May 2011
An all-electron scalar relativistic calculation on AunPt (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 AunPt (n = 1−12) clusters may be generated by substituting Pt atom for one gold atom of the Aun+1 cluster at the highest coordinated site. Compared with corresponding pure Aun+1 cluster, the lowest energy geometries of AunPt 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 Aun+1 cluster. By substituting Pt atom for one gold atom of Aun+1 cluster at the highest coordinated site, the relatively stable and inactive odd-numbered Aun+1 cluster becomes the relatively unstable and reactive odd-numbered AunPt cluster, and the relatively unstable and reactive even-numbered Aun+1 cluster becomes the relatively stable and inactive even-numbered AunPt cluster chemically and electronically. All the AunPt clusters prefer low spin multiplicity. The even-numbered AunPt clusters are found to exhibit zero magnetic moment and the odd-numbered AunPt clusters are found to possess magnetic moment with the value of 1 μB. The odd-even alterations of magnetic moments and electronic configurations for AunPt clusters are very obvious and may be simply understood in terms of the electron pairing effect.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2011