Stability Of Silicon-Copper Alloy Clusters （CuSi）_n,（Cu₂Si）_n,（Cu₅Si₃）_n

Using the density functional theory（DFT）at the B3LYP level,the geometries,relative stabilities,and electromagnetic characteristics of silicon-copper alloy clusters（CuSi）_n（n=1-8）,（Cu₂Si）_n（n=1-6）,（Cu₅Si₃）_n（n=1-3）have been systematically investigated.And the main results are as follows:For（CuSi）_n（n=1-8）clusters,when n=1,the cluster is a linear structure;when n=2,the cluster presents tetrahedral structure;when n=3,the cluster begins to grow in three-dimensional structure of blocks.At the beginning of n=6,the cluster appears as a cage-like structure,and the Cu atoms are trapped inside the cage-like structure.For（Cu₂Si）_n（n=1-6）clusters,when n=1,the cluster is a two-dimensional plane triangular structure;starting from n=2,the clusters grow in a three-dimensional structure.For（Cu₅Si₃）_n（n=1-3）clusters,when n=1,the ground state structure of the cluster is a hendecahedral structure composed of two pentahedrons.When n=2 and 3,the clusters show a cage-like structure.With the increase of the size of the cluster（CuSi）_n（n=1-8）,（Cu₂Si）_n（n=1-6）,（Cu₅Si₃）_n（n=1-3）,the average binding energy of each atom is gradually increased,indicating that the stability of the cluster is gradually enhanced.For clusters of the same size,the average binding energy of each atom of alloy clusters is always higher than that of pure copper clusters,suggesting that the silicone hybrid doping enhanced the stability of the pure copper clusters.The analysis of the average bond length indicates that the interaction between si-si in the alloy cluster is the strongest,and the interaction between si-cu is second,and the interaction between cu-cu is the weakest.The analysis of HOMO-LUMO energy gap and chemical hardness of silicon-copper alloy clusters show that:（CuSi）₂,（CuSi）₄,（Cu₂Si）₄,Cu₅Si₃,these clusters have strong chemical inertness.The Hirshfeld population analysis and differential charge density analysis of the clusters show that,besides CuSi,the electron is always transferred to Si atom by Cu atom,and Cu atom is less electronegative.Hirshfeld population analysis and PDOS analysis consistently show that the total magnetic moments of（CuSi）_n and（Cu₅Si₃）_n clusters show odd-even oscillations,and the total magnetic moment of（Cu₂Si）_n clusters is always 0μ_B.The hybridization characteristics of s-p-d electron orbit in silicon-copper alloy clusters are obvious.The static polarizabilities of silicon-copper alloy clusters are mainly distributed in the three directions of XX,YY and ZZ,and that in other directions are less,and many clusters are zero.The static mean polarizabilities per atom of the silicon-copper alloy clusters decreases with the increase of the size of the cluster,indicating that the electronic structures of the alloy clusters tend to be compact with the increase of atoms.