Electron binding energies of anionic magnesium clusters and the nonmetal-to-metal transition

The binding energies of the two most external electrons in Mg-n(-), n = 2-22, clusters are computed using the gradient-corrected density functional theory and a new scheme for converting the Kohn-Sham eigenenergies into electron removal energies. The computations are performed for the anionic clusters considered in the most stable configurations of both Mg-n(-) and Mg-n. The results are compared with photoelectron spectroscopy data [O. C. Thomas et al., following Letter, Phys. Rev. Lett. 89, 213403 (2002)], and their implications for the finite-size analog of the nonmetal-to-metal transition are analyzed.