The Extended Hubbard Model at Large Interaction
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The half-filled Extended Hubbard model (i. e., the Hubbard model including nearest-neighbor interaction) is considered at strong coupling in fourth order perturbation theory (4thOPTh). The ground state energies in the spin- and charge-density-wave phases and the resulting phase diagram are calculated in one, two, three and higher dimensions. Quite generally one finds that second order perturbation theory alone is valid only at unrealistically large values of the interaction parameters U and V. In one dimension it is shown that, for U/t larger 6, 4thOPTh leads to excellent agreement with existing Monte Carlo data.
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- In d = 1 the transition is known to be second order at weak and first order at strong interaction. In higher dimensions (d → ∞) the transition is first order for all U and V.Google Scholar
- V.J. Emery, in Highly Conducting One-Dimensional Solids, J. Devreese, R. Evrand and V. van Doren, eds. (Plenum, New York, 1979).Google Scholar
- P.G.J. van Dongen Phys. Rev. B, accepted for publication.Google Scholar
- I am grateful to Dr. Hirsch for making these data (not explicitly contained in Ref. ) available to me. The actual error bars on the MC data were probably much smaller than the ones quoted.Google Scholar
- W. Metzner, PhD-thesis, RWTH Aachen (1990).Google Scholar