Stablities and magnetism of the ground-state structures of CoAl_N(N=2-11) clusters

The geometry structures of CoAlN(N=2-11)clusters have been optimized,and the magnetic moment of Co atom of CoAlN(N=2-11)clusters have been investigated by using generalized gradient approximation of density functional theory.The equilibrium geometries with different spin multiplicity as well as the ground states structures were obtained.Also,more emphysises have been placed on the effects of the sp-d hybridization of Co atom on the stabilities and magnetism.The results indicate:when the number of N is even,the spin multiplicity is doublet in which the magnetic moment of Co atom reduce continouely while it is singlet(except the CoAl5 is triplet)as the number of N is odd where the magnetic moment of Co atom is quenched.The Co atom falls into the interior site of the host cluster from N=8,which results in the lower symmetries and the enhancement of stabilities of the clusters.The sp-d hybridization of Co atom enhences the stabilities of the CoAlN(N=2-11)clusters but reduces the magnetic moment of Co atom of the CoAlN clusters with doublet and triplet multiplicity.N=3,8,10 is the magic number of the CoAlN(N=2-11)clusters.