IMPORTANCE OF ELECTRON-ELECTRON INTERACTION FOR HARMONIC-GENERATION

We compute the spectrum of the high-order harmonic radiation that is e mitted during the interaction of a short laser pulse with a one-dimens ional two-electron system. The flexibility of our numerical approach a llows us to determine the relative importance of the e-e interaction f or the scattered light by coupling only one of the two electrons to th e field. The harmonic emission from each electron can then be determin ed. The e-e interaction appears to be at least as important as the cou pling of one electron to the laser field. The coupling of both electro ns to the field enhances the nonlinear response of the system.