A Study On The Structures And Stabilities Of Aluminum-nickel Nanoalloy Clusters

In this paper, with a genetic algorithm we study the structures andstabilities of aluminum and nickel clusters and aluminum-nickelnanoalloy clusters, modeled by many-body Gupta potential, It makesclear that for pure nickel clusters, the lowest structures are based onicosahedral packing, while the pure aluminum clusters tend to formamorphous structures. This result is consistent with the previous works,indicating the genetic algorithm is suitable in the optimization of clusterstructure. Because of the presence of the geometrical isomers, it is moredifficult for us to find the lowest energy structure of the nanoalloy clustersthan the pure metallic clusters. Based on the genetic algorithm, weinvestigate the structure of the aluminum-nickel nanoalloy clusters. Itshows that the structure of the lowest energy bimetallic clusters exhibitprimarily icosahedral packing. When the number of aluminum atoms isgreater than that of nickel atoms, the clusters tend to form layeredstructures. While in the opposite situation, the cluster tends to showrandom Al-Ni mixing. Especially, we find that in some cases, thereplacement of a single aluminum atom by one or a few nickel atoms canconvert the structure to be more symmetrical, similar to that of the nickelcluster. It is common believed that when N<14, AlxNiy(x+y=N)nanoalloy clusters mainly based on icosahedron. Our results, however,first reveal that Al8Ni2 has a compact, oblate, and geometry and similarsituation also occur at Al9Ni2.