Probing the structural and electronic properties of bimetallic chromium-gold clusters Cr_mAu_n (m + n ≤ 6): comparison with pure chromium and gold clusters

摘要

Bimetallic chromium-gold Cr_mAu_n (m+n≤6) clusters are systematically investigated using the density functional theory at PW91P86 level with LanL2TZ basis set to understand the evolution of various structural, electronic, magnetic, and energetic properties as a function of size (m+n) and composition (m) of the system. Theoretical results show a logical evolution of the properties depending on the size and the composition of the system. Cr_m clusters clearly prefer 3D structures while Au_n clusters favor planar configurations. The geometry of the bimetallic Cr_mAu_n clusters mainly depends on their composition, i.e., clusters enriched in Cr atoms prefer 3D structures while increasing Au contents promotes planar configurations. The stability is maximized when the composition of binary Cr_mAu_n clusters is nearly balanced. Meanwhile, the number of hetero Cr?Au bonds and charge transfer from Cr to Au are maximized for clusters with m≈n. The most probable dissociation channels of the Cr_mAu_n clusters are calculated and analyzed. Natural population analysis reveals that Au atoms tend to be negatively charged while Cr atoms tend to be positively charged. Combined with the trend that Au atoms favor the surface/edges/vertices and Cr atoms tend to be inside, the outer part of the cluster tends to be negatively charged, and the inner part tends to be positively charged.