Temperature dependence of spectral functions for the one-dimensional Hubbard model: Comparison with experiments

We study the temperature dependence of the single particle spectral function as well as the dynamical spin and charge structure factors for the one-dimensional Hubbard model using the finite temperature auxiliary field quantum Monte Carlo algorithm. The parameters of our simulations are chosen so to at best describe the low temperature photoemission spectra of the organic conductor tetrathiafulvalene-tetracyanoquinodimethan (TTF-TCNQ). Defining a magnetic energy scale T-J, which marks the onset of short ranged 2k(f) magnetic fluctuations, we conclude that for temperatures T < T-J the ground state features of the single particle spectral function are apparent in the finite temperature data. Above T-J spectral weight transfer over a scale set by the hopping t is observed. In contrast, photoemission data point to a lower energy scale below which the spectral weight transfer occurs. Discrepancies between Hubbard model calculations and experiments are discussed.