Geometry and stability of Cu(n)N (n=1-6) and Cu(3n)N(n) (n=1-5) clusters.

The gradient-corrected density functional calculation is applied to search the lowest-energy configurations of Cu(n)N (n=1-6) clusters and the calculation indicated that Cu(3)N cluster is the most stable one. Based on the result, we further investigate the equilibrium geometries and stabilities of the Cu(3n)N(n) (n=2-5) clusters. We found that in Cu(6)N(2) cluster, N atoms formed a separate N(2) molecule away from the other part of the cluster. Furthermore, it was shown that the lowest-energy configurations of Cu(3n)N(n) (n=3-5) are stable with the nitrogen atoms well separated by the copper atoms. Therefore, it can be concluded that the Cu(3)N cluster can be used as a building block for the construction of the cluster-assembled compounds.