1 Elementary electronic excitations in one - dimensional continuum and lattice systems

We systematically investigate the mode dispersion and spectral weight of the elementary excitation spectra in one-dimensional continuum and lattice electron systems by using the RPA, the Luttinger liquid model, and the Hub-bard model. Both charge and spin excitations are studied in details and compared among the theoretical models. For the lattice Hubbard model we use both Bethe-ansatz equations and Lanczos-Gagliano method to calculate dispersion and spectral weight separately. We discuss the theoretically calculated elementary excitation spectra in terms of the experimental inelastic light (Raman) scattering spectroscopy of 1D semiconductor quantum wire systems. Our results show that in the polarized (i.e. non-spin-flip) Raman scattering spectroscopy, only the 1D charge density excitations should show up with observable spectral weight with the single particle excitations (in RPA) or singlet spin excitations (in the Luttinger model and the Hubbard model) having negligible spectral weight. The depolarized (spin-flip) Raman scattering spectra manifest the spin density or the triplet spin excitations. We also provide a qualitative comparison between the continuum and the lattice 1 1D elementary excitation spectra.