A Density Functional Theory Study On PtIr_n^0,±（n=1⁵） Clusters

In this paper, Gaussian03program based on density functional theory（B3LYP method）is applied. The geometric structures of PtIr_n^0,±（n=1⁵） clusters are optimized systematicallyat Lanl2dz level. Their physical and chemical properties are studied, as well as theirstructural stability. The research contents and results are as follows.Firstly, The possible geometrical configurations of PtIr_n^0,±（n=1⁵） clusters areoptimized. For the ground state structures, the stability is calculated and analyzed. Theresults show that there are many different isomerides in PtIr_n^0,±（n=1⁵） clusters, and theclusters with less atoms are two-dimensional graphic structures, while these clusters withmore atoms are three-dimensional graphic structures. With the increase of atoms number,the thermodynamics stability of the clusters is better and better. And the stability of thePtIr3+cluster is the best. Compared with pure iridium clusters, it is easier for PtIrn（n=1⁵）clusters to get electron, and the nonmetallicity of PtIr_n^0,±（n=1⁵） clusters is stronger. Iridiumatoms play a dominant role in the stability of PtIr_n^0,±（n=1⁵） clusters.Secondly, for the ground state structures of PtIr_n^0,±（n=1⁵） clusters, The NBO, thespectrum, the aromatic characteristics and the polarizability are analyzed The study resultsshow, platinum atom gain charge when forming clusters, and the situation of iridium iscomplex, some iridium atoms gain the charge and the other lose the charge. Parts of thecharge iridium atoms lose transfer to platinum atom and the other iridium atoms. There aremore vibration peaks in IR and Raman spectrum of PtIr_n^0,±（n=1⁵） clusters when thenumber of atoms is more, and the vibration peaks of the IR and Raman spectrum of PtIr4-cluster are strongest. The PtIr3、PtIr5、PtIr5+clusters are aromatic. The bond interactionbetween atoms of the PtIrn0,±（n=1-5） clusters present a rising tendency with the increase ofatoms number, and the electronic structure of PtIr3、PtIr5+clusters is unstable relatively, andthe delocalization effect is strong. With the increase of atoms number, the stability of theelectronic structure of anionic clusters present a rising tendency, the delocalization effectdecreases gradually.