DIPOLE EXCITATION OF NA CLUSTERS WITH A NONLOCAL ENERGY DENSITY-FUNCTIONAL

The elementary dipole excitations of the ionized clusters Na9+, Na21and Na41+ are investigated by solving the equations of the Random-Phas e Approximation. The ground and excited states are described using the jellium model for the ionic background and a non-local energy density functional for the valence electrons. Non-local effects are specifica lly analyzed. The excitation energies thus obtained approach better th an those of the Local Density Approximation both the full Hartree-Fock and the experimental results.