Density functional method (DFT) has been combined with global minimum techniques into hybrid schemes: The equilibrium geometries and electronic properties of little cluster Nb_n (n＝2～6) clusters were determined via DFT computations. The potential function was constructed with parameters fitted to calculated results, and a global minimum "basin-hopping" algorithm was used to obtain minimum-energy structures of Nb clusters for n＝7～20. The results are in good agreement with experiments and other calculations.

Key words: Nb cluster, DFT, potential energy function, global optimization