COLLECTIVE E-LAMBDA EXCITATIONS OF SURFACE CHARACTER IN SPHERICAL ANDDEFORMED SODIUM CLUSTERS - VIBRATING POTENTIAL MODEL

The self-consistent vibrating potential model (VPM) is extended for th e description of E lambda surface collective excitations in alkali met al clusters with practically any kind of static deformation. The case of spherical clusters is also covered. Any single-particle potentials and valence electron densities for which the coefficients of the multi pole expansion are known can be used within the model. The strength fu nction method incorporated into the model allows one to avoid solving the equations for every state and, as a result, simplifies the calcula tions drastically. The model is of a quite general character and can a lso be used for description of giant resonances in atomic nuclei if th e Coulomb terms are neglected. The VPM is applied to calculate the El, E2 and E3 excitations in spherical (Na-8, Na-20 and Na-40) and deform ed (Na-10, Na-18 and Na-26) clusters.