Appearance of metallic features in small tungsten clusters

The structures and properties of $W_{n}$ ($n=2$--14) clusters were studied by using the density functional theory (DFT) at LSDA level. The most stable structures of $W_{n}$ ($n=2$--14) clusters with global minimum were determined. The average binding energy ($E_{b})$, the first and second difference of total energy (${\it\Delta} E$, ${\it\Delta}_{2}E)$, the vertical detachment energy ({VDE}), and the HOMO-LUMO gap versus the size were also discussed. The abrupt decrease of {VDE} and HOMO-LUMO gap at size $n=8$ and 10 implied that tungsten clusters of $W_{8}$ and $W_{10}$ appeared to have metallic features. These changes were also accompanied by the delocalization of electron charge density and the strong hybridization between $5d$ and $6s$ orbits in $W_{8}$ and $W_{10}$ clusters. Our results are in good agreement with the available experimental data.