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Correlated electrons in one spatial dimension have very unusual
properties such as the dynamical separation of spin and charge degrees of freedom. Typically, dynamical correlation functions of these systems are investigated with field theoretical methods that are valid in the limit of vanishingly low energies. However, there are few reliable results at finite energies which can be directly compared with spectra of scattering experiments. It has therefore been difficult to find direct spectroscopic evidence of spin-charge separation in experimental realizations of quasi one-dimensional electron systems.
The Dynamical Density-Matrix Renormalization Group [1] can accurately determine spectral properties of correlated one-dimensional lattice models for all energy scales and interaction strengths. We use this method to calculate the one-particle spectral function of Hubbard chains both above and below half-filling [2]. We argue that the ARPES spectrum of the quasi one-dimensional organic conductor TTF-TCNQ [3] can be consistently explained by essentially uncoupled TTF and TCNQ chains with short-ranged Coulomb interactions at electron densities n=1.4 and n=0.6, respectively. [1] E. Jeckelmann, Phys. Rev. B 66, 045114 (2002); [2] H. Benthien et al., Phys. Rev. Lett. 92, 256401 (2004); [3] R. Claessen et al., Phys. Rev. Lett. 88, 096402 (2002). |