EFFECT OF ELECTRON-ELECTRON INTERACTIONS ON THE AVERAGE POLARIZABILITY OF A MESOSCOPIC SYSTEM

A comparison between an analytical calculation of the polarizability o f a mesoscopic interacting system in the random-phase approximation an d numerical exact diagonalization results is presented. While for weak interactions the analytical calculation fits the numerical results ra ther well, deviations appear for stronger interactions. This is the re sult of the appearance of intermediate-range correlations in the elect ron density, which suppresses the polarizability below its classical v alue. The relevance to quantum-dot systems is discussed.