A DFT Research For Structures And Properties Of W_mSi_n^0,± Clusters

In this paper, density functional theory (DFT) calculations for W_mSi_n^0,±(m=1⁶,n=1, 2) clusters were performed with Gaussian 03 packages at the B3LYP/Lanl2DZ level. We optimized the structures and studied the properties of the clusters at their ground state. Our main results are list as follows:(1) The structures of W_nSi₁^0,± can be obtained following a similar growth pattern as the case of W_n+1 clusters. The cationic and anion clusters could maintain the structure of their corresponding neutral one except the cases of W₃Si₁+and W₅Si₁^-. Compared with other clusters, the WSi₁ cluster is prone to accept one electron becoming an anion, and the W₅Si₁ is easier to lose one electron turning into a cation. The W₅Si₁^- cluster is more active than other ones while the W3Si cluster is more inert. The W₃Si₁ and W₅Si₁^- are both aromatic clusters. The W₁Si₁^0,± clusters can show ferromagnetic property. All the W_nSi₁^0,±(n=1⁵) clusters have non-rigid property. As the number of W atoms increases in the clusters, the direction of charge transfer between W and Si could change.(2) The two Si atoms of the clusters W_nSi₂^0,±(n=2⁵) do not form chemical bond with each other in the most stable structures as well as some isomers with higher energy. The clusters W₅Si₂^0,± and W₃Si₂⁺ have similar structures with the ones of W7 and W₅^0,± respectively. The W₅Si₂^- cluster can be regarded as an ideal composite material. W₂Si₂,W₂Si₂-,W₅Si₂⁺ are all aromatic clusters, in which electron is transferred from Si to W atoms. The W₁Si₂^0,± clusters can show ferromagnetic property. All other clusters have non-rigid property except the cluster W₄Si₂^-.(3) The structures of the most stable and metastable W₆Si_n^0,±(n=1, 2) are all three-dimensional, and the two Si atoms do not form chemical bond with each other in W₆Si₂^0,± clusters. The W₆Si₂^0,± clusters are all aromatic, in which W6Si2 cluster has the most aromaticity. In all the W₆Si_n^0,±(n=1, 2) clusters, electron is transferred from Si to W atoms. The magnetic properties were also studied, which show that the W₆Si₁ cluster is a non-magnet, the W₆Si₁⁺ and W₆Si₂^0,± are clusters with weak ferromagnetic property, and the cluster W₆Si₁- is a weak antiferromagnet.