Europhys. Lett.
Volume 70, Number 4, May 2005
Page(s) 492 - 498
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 15 April 2005
Europhys. Lett., 70 (4), pp. 492-498 (2005)
DOI: 10.1209/epl/i2005-10020-8

Tomonaga-Luttinger parameters for doped Mott insulators

S. Ejima1, F. Gebhard1 and S. Nishimoto2

1  Fachbereich Physik, Philipps-Universität Marburg - D-35032 Marburg, Germany
2  Institut für Theoretische Physik, Universität Göttingen D-37077 Göttingen, Germany

received 28 February 2005; accepted in final form 31 March 2005
published online 15 April 2005

The Tomonaga-Luttinger parameter $K_{\rho}$ determines the critical behavior in quasi-one-dimensional correlated electron systems, e.g., the exponent $\alpha$ for the density of states near the Fermi energy. We use the numerical density-matrix renormalization group method to calculate $K_{\rho}$ from the slope of the density-density correlation function in momentum space at zero wave vector. We check the accuracy of our new approach against exact results for the Hubbard and XXZ Heisenberg models. We determine $K_{\rho}$ in the phase diagram of the extended Hubbard model at quarter filling, $n_{\ab{c}}=1/2$, and confirm the bosonization results $K_{\rho}=n_{\ab{c}}^2=1/4$ on the critical line and $K_{\rho}^{\ab{CDW}}=n_{\ab{c}}^2/2=1/8$ at infinitesimal doping of the charge-density-wave (CDW) insulator for all interaction strengths. The doped CDW insulator exhibits exponents $\alpha>1$ only for small doping and strong correlations.

71.10.Fd - Lattice fermion models (Hubbard model, etc.).
71.30.+h - Metal-insulator transitions and other electronic transitions.
71.10.Hf - Non-Fermi-liquid ground states, electron phase diagrams and phase transitions in model systems.

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