Collective excitations in realistic quantum wires

We have used the Hartree-Fock random phase approximation to study the interacting electron gas in a quantum wire. The spectra of intersubband spin-flip excitations reveal a considerable red shift with respect to single-particle Hartree-Fock energies. That signals the appearance of collective intersubband spin-density excitations due to the exchange interaction. The long-wavelength dispersions of the intrasubband collective spin-density excitations are linear but the sound velocities are renormalized due to the exchange interaction and screening. The in-phase intrasubband charge-density excitation has the long-wavelength form q[-ln(q)]^1/2. We found good qualitative agreement of our results with experimental observations.