Effective single-band models for the high-{ital T}{sub {ital c}} cuprates. I. Coulomb interactions
- Philips Research Laboratories, Prof. Holstlaan 4, 5656 AA Eindhoven (The Netherlands)
- DRA Electronics Sector, St. Andrews Road, Great Malvern, Worcestershire WR14 3PS (England)
Starting with the three-band extended Hubbard model (or {ital d-p} model) widely used to represent the CuO{sub 2} planes in the high-{ital T}{sub {ital c}} cuprates, we make a systematic reduction to an effective single-band model using a previously developed cell-perturbation method. The range of parameters for which this mapping is a good approximation is explored in the full Zaanen-Sawatzky-Allen diagram (copper Coulomb repulsion {ital U}{sub {ital d}} versus charge-transfer energy {var_epsilon}), together with an investigation of the validity of mapping to an effective charge-spin ({ital t-J-V}) model. The variation of the effective single-band parameters with the parameters of the underlying multi-band model is investigated in detail, and the parameter regime where the model represents the high-{ital T}{sub {ital c}} cuprates is examined for specific features that might distinguish it from the general case. We consider the effect of Coulomb repulsions on oxygen ({ital U}{sub {ital p}}) and between copper and oxygen ({ital V}{sub {ital pd}}). The reduction to an effective single-band model is generally valid for describing the low-energy physics, and that {ital V}{sub {ital pd}} and {ital U}{sub {ital p}} (unless unrealistically large) actually slightly improve the convergence of the cell-perturbation method. Unlike in the usual single-band Hubbard model, the effective intercell hopping and Coulomb interactions are different for electrons and holes. We find that this asymmetry, which vanishes in the extreme Mott-Hubbard regime ({ital U}{sub {ital d}}{lt}{var_epsilon}), is quite appreciable in the charge-transfer regime ({ital U}{sub {ital d}}{approx_gt}{var_epsilon}), particularly for the effective Coulomb interactions. We show that for doped holes (forming Zhang-Rice singlets) on neighboring cells the interaction induced by {ital V}{sub {ital pd}} can be attractive due to locally enhanced {ital pd} hybridization, while this can`t occur for electrons.
- OSTI ID:
- 283555
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 53, Issue 13; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
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