Ca neutral clusters: a two-step and DFT benchmark.

Electronic and structural properties of calcium clusters with a varying size range of 2-20 atoms are studied using a two-step scheme within the and density functional theory (DFT) with generalized gradient approximation (GGA). The GGA overestimates the binding energies, optimized geometries, electron affinities, and ionization potentials reported in the benchmark. The ground-state structure geometry and binding energy were obtained from the DFT for the ground-state structure of each cluster.