Theory of charge-density and spin-density excitations for two electrons in a circular quantum dot

We calculate charge- and spin-density excitation spectra for two electrons in a two-dimensional circular hard-wall confined quantum dot. These excitation spectra may be measured by inelastic light scattering. Spectra for arbitrary dot sizes and wave-vector shifts of the light are calculated using an exact diagonalization in the basis of Slater determinants thus including direct, exchange and correlation interaction effects exactly. In the dipole approximation the main charge-density resonance is blueshifted and the main spin-density resonance is redshifted for decreasing electronic density. Beyond the dipole approximation new modes appear for decreasing electronic density.