STRUCTURE AND STABILITY OF AL-DOPED SMALL NA CLUSTERS - NANAL (N=1,10)

We have investigated the ground-state geometries of aluminum-doped sod ium clusters NanAl (n=1,10) using an ab initio molecular-dynamics meth od. It is seen that a single Al impurity atom affects significantly th e geometries of small Na-n (n less than or equal to 6) clusters, where as the effect is less pronounced for large clusters. Our results show an early appearance of nonplanar ground-state geometries and it is obs erved that for n greater than or equal to 6 the Al atom gets trapped i nside the Na cage. The stability of these clusters has been examined f rom the systematic analysis of energetics. This indicates Na5Al and Na 7Al having 8 and 10 valence electrons to be the stable clusters.