A NEW FORMULATION OF THE DYNAMIC-RESPONSE OF MANY-ELECTRON SYSTEMS AND THE PHOTOABSORPTION CROSS-SECTION OF SMALL METAL-CLUSTERS

Static polarizabilities and photoabsorption cross sections of clusters Na7-, Na8, Na-19- Na-20 are calculated, based on the spherical jellium model including the self-interaction correction (SIC) of Perdew and Zunger. To this end, a new formulation of the theory of the linear response is presented, which is suitable for general, self-interaction corrected, many-electron systems. The results obtained display an overall agreement with available experimental data, offering a systematic improvement with respect to the standard TDLDA. Furthermore, the cross sections of the negatively charged clusters are found to be dominated by a broad peak in the visible region, whose line width can be related to the lifetime of the surface plasmon against electron detachment.