Stability and electronic properties of W_n X(n=1-7, X= Cu, Mo) clusters

The geometries, relative stabilities and electronic properties of a variety of possible structures of $W_{n}X$ (n = 1 -7, $X=Cu$, Mo) clusters were systematically investigated by using density functional theory (DFT) method at the generalized gradient approximation (GGA) level for ground state structures. The results indicate that the ground state of WX is linear and the shift from planar to three-dimensional structures occurs at n = 3. The structures of tungsten clusters doped with Mo atom are tighter than those doped with copper ones. The calculated second-order differences in energies, dissociation energies and HOMO-LOMO energy gaps show pronounced odd-even oscillation behaviors. Particularly, $W_{n}Cu$ clusters with odd-number atoms keep a higher relative stability than their neighboring ones, but $W_{n}Mo$ clusters go by contraries. The magnetic properties of $W_{n}Cu$ and $W_{n}Mo$ are both weak except for WCu.