THEORY OF METALLIC CLUSTERS - ASYMPTOTIC SIZE DEPENDENCE OF ELECTRONIC-PROPERTIES

For a spherical metallic cluster of large radius R, the total energy is E = alpha-4-pi-R3/3+sigma-4-pi-R2+gamma-2-pi-R, the chemical potential is mu = - W - c/R, and the first ionization energy I and electron affinity A are - mu +/- 1/2(R + d). By solving the Euler equation within the Thomas-Fermi-Dirac-Gombas-Weizsacker-4 approximation for jellium spheres with up to 10(6) electrons, we extract the surface energy sigma, curvature energy gamma, work function W, and constants c and d. The constant c is not zero, but neither is it - 1/8, the prediction of the image-potential argument. We trace c to the second- and fourth-order density-gradient terms in the kinetic energy, which are present even in systems with no image potential. However, the constant d is found to be the distance from a planar surface to its image plane. In the absence of shell-structure oscillations, the asymptotic forms hold accurately even for very small clusters; this fact suggests a way to extract the curvature energy of a real metal from its surface and monovacancy-formation energies. We also discuss asymptotic R-1 corrections to the electron density profile and electrostatic potential of a planar surface.