Structural and electronic properties of small copper clusters: a first principles study

Equilibrium geometries and electronic properties of neutral Cu_n (n = 2, 3, 4, 6, 8, 10) clusters are determined via first principles calculations which treat s and d electrons on an equal footing. Overall, we find ground state and local minimum structures similar to those of Na_n. However, Cu_n clusters tend to prefer more compact arrangements. Electronic states with atomic s-character are strongly hybridized with d-states and located mostly at the band edges. Angular decomposition of the electronic wavefunctions in Cu_n clusters shows that their shell model character is significantly less pronounced than in Na_n clusters.