THEORY OF CHARGE-DENSITY AND SPIN-DENSITY EXCITATIONS FOR 2 ELECTRONSIN A CIRCULAR QUANTUM-DOT

We calculate charge- and spin-density excitation spectra for two elect rons in a two-dimensional circular hard-wall confined quantum dot. The se excitation spectra may be measured by inelastic light scattering. S pectra for arbitrary dot sizes and wave-vector shifts of the light are calculated using an exact diagonalization in the basis of Slater dete rminants thus including direct, exchange and correlation interaction e ffects exactly. In the dipole approximation the main charge-density re sonance is blueshifted and the main spin-density resonance is redshift ed for decreasing electronic density. Beyond the dipole approximation new modes appear for decreasing electronic density.