LAUSR

Abstract The Hume-Rothery alloy phases of the main-group elements are rather rare, of which the phase stability mechanisms are decided by the electronic effects. The intermetallic compound Be-Pt alloy is a member of this family, but structural and electronic characters of them at nanometer scale still remain unclear. In this work, the geometric structures, stabilities and electronic properties of BenPt clusters (n = 1-10) are first investigated using the method combining the genetic algorithm with density function theory (DFT). Benchmark calculations indicate that the PBE-D3 functional is reliable in predicting the energetic sequences of four isomers of Be4Pt cluster compared to the high-level coupled cluster method. In general, the most structures of the alloy clusters can be obtained by replacing one beryllium atom in the pure beryllium (Bem, m = 2-11) clusters with a Pt atom. We found that the Be4Pt and Be10Pt clusters are two very stable 8e/20e superatoms in this series, respectively, where the electronic structure of Pt atom is d10. Analyses of electrostatic potential surfaces show that these two clusters have significant σ-holes with most positive potential regions, which can be seen as binding sites with Lewis bases. When a CO molecule is adsorbed on the superatom clusters, the C=O stretching frequency has a large red-shift and the bond length is slightly elongated, due to the electrons of the clusters transfer to the anti-bond π orbital of CO. This work gives inferences for further understanding structural characters of the binary alloy from the nanoscale view.