Tuning the bond-order wave phase in the half-filled extended Hubbard model

Kumar, Manoranjan and Ramasesha, S and Soos, ZG (2009) Tuning the bond-order wave phase in the half-filled extended Hubbard model. In: Physical Review B, 79 (3). 035102-1-8.

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Abstract

Theoretical and computational studies of the quantum phase diagram of the one-dimensional half-filled extended Hubbard model (EHM) indicate a narrow bond-order wave (BOW) phase with finite magnetic gap E-m for on-site repulsion U < U-*, the critical point, and nearest-neighbor interaction V-c approximate to U/2 near the boundary of the charge-density wave (CDW) phase. Potentials with more extended interactions that retain the EHM symmetry are shown to have a less cooperative CDW transition with higher U-* and wider BOW phase. Density-matrix renormalization group is used to obtain E-m directly as the singlet-triplet gap, with finite E-m marking the BOW boundary V-s(U). The BOW/CDW boundary V-c(U) is obtained from exact finite-size calculations that are consistent with previous EHM determinations. The kinetic energy or bond order provides a convenient new estimate of U-* based on a metallic point at V-c(U) for U < U-*. Tuning the BOW phase of half-filled Hubbard models with different intersite potentials indicates a ground state with large charge fluctuations and magnetic frustration. The possibility of physical realizations of a BOW phase is raised for Coulomb interactions.

Item Type:	Journal Article
Additional Information:	Copyright of this article belongs to American Physical Society.
Keywords:	charge density waves;critical points;frustration;Hubbard model;magnetic transitions;renormalisation.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	24 Mar 2009 09:56
Last Modified:	19 Sep 2010 05:27
URI:	http://eprints.iisc.ernet.in/id/eprint/19171

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