Abstract: Possible geometrical configurations of PtIr_n^0,± (n=1~5) clusters are optimized with density functional theory(b3lyp) at lanl2dz level.For ground state structures of PtIr_n^0,± (n=1~5) clusters,stability is calculated and analyzed.It shows that there are many isomerides in PtIr_n^0,± (n=1~5) clusters.Clusters with less atoms are two-dimensional graphic structures,while clusters with more atoms are three-dimensional graphic structures.With increase of atoms,thermodynamics stability of clusters is better.And stability of PtIr₃⁺ cluster is the best.Compared with pure iridium clusters,it is easier for PtIr_n(n=1~5) clusters to get an electron,Nonmetallicity of PtIr_n(n=1~5) clusters is stronger.iridium atoms play a dominant action in stability of PtIr_n^0,± (n=1~5) clusters.

Key words: PtIr_n^0,± (n=1~5)clusters, structures and stability, density functional theory