Research For Structure And Thermodynamic Properties Of Wolframium And Aluminum Mixed Cluster

There have been much research about mixed cluster, but research for two kinds ofmaterials with much different property is still very limited. Here，the aluminum andwolframium mixed clusterAl_mW_n are studied by the methed of molecular dynamics. Onthe one hand, study on the stability ofAlm_Wn geometry structure is carried out; on theother hand, the thermodynamics property of mixed clusterAl_mW_n are analysied.First of all, the ground state geometry structures of the mixed clusterAl_mW_n （2≦n≦29） are obtained by the method of simulate-annealing. It is found that themixed cluster geometry structures are regular when the numbet of total atoms close tomagic number. But most geometry structures of mixed cluster are irregular, which areformed by adding atoms on some basic regular sub-structure. In the mixed cluster the Alatoms are located around the cores formed by the W atoms. Then the curves of thesecond-order differenceV₂Echanged with m are made. The stability of each clusterAl_mW_n （2≦n≦29） is anslysised. It was concluded that, different from the clustersformed by one kind of atom, the second-order difference score of the mixed cluster of didnot some present regular rules. For example: odd number and even number alternatelypresent to wave crest and wave trough, but appear phenomenon that with m continuouslyvariable, in some stage of m dereferencing, the second-order difference score of mixedcluster almost equal, accounting for a lot of cluser has the same stability.Secondly, in this paper the thermodynamic property and melting behavior of mixedcluster with13or19atoms are discussed. It is found that the mixed cluster meltingbehavior is related to the component. Different components determine different meltingtemperature. The melting temperature rise with the increase of the number of W atom; It isfound out that secondary-melting appear in melting process of some mixed cluster. That isto say, the δ value of cluser presents two-jumpping. By analsising the δ curves of thesingle atom, it is found that this phenomenon origins from of the earlier melting of Alatoms prior to that of the W atoms.