Effects of electron correlation and geometrical structure on stability of metal clusters

A self-consistent calculation of the electronic structures of alkali-metal clusters based on the spherical jellium model has been performed by using the spin-polarized local-density-functional (LDF) approximation and its self-interaction-corrected (SIC) version. The results for the total energy of the jellium sphere lead to the stabilization of the cluster at the shell-closing numbers and the half-filled-shell ones with the high-spin configuration. The SIC calculation much improves the shortcoming of the LDF approximation and gives the correct description of the fragmentation process and the ionization potential. The effects of the nonspherical field due to certain geometrical arrangements of atoms are examined within the perturbative treatment. It is shown that the nonspherical perturbation overcomes the exchange stabilization making the half-filled-shell magic number invalid while an enhancement of the stabilization at the shell-closing numbers is still expected, particularly in the SIC version.