The Hubbard model with intersite interaction within the Composite Operator Method

Abstract

We study the one- and two- dimensional extended Hubbard model by means of the Composite Operator Method within the 2-pole approximation. The fermionic propagator is computed fully self-consistently as a function of temperature, filling and Coulomb interactions. The behaviors of the chemical potential (global indicator) and of the double occupancy and nearest-neighbor density- density correlator (local indicators) are analyzed in detail as primary sources of information regarding the instability of the paramagnetic (metal and insulator) phase towards charge ordering driven by the intersite Coulomb interaction. Very rich phase diagrams (multiple first and second order phase transitions, critical points, reentrant behavior) have been found and discussed with respect to both metal-insulator and charge ordering transitions: the connections with the experimental findings relative to some manganese compounds are analyzed. Moreover, the possibility of improving the capability of describing cuprates with respect to the simple Hubbard model is discussed through the analysis of the Fermi surface and density of states features. We also report about the specific heat behavior in presence of the intersite interaction and the appearance of crossing points.

15 pages, 36 figures

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Cited by in corpus (16)

• The Hubbard model within the equations of motion approach
• Non-Perturbative Treatment of Charge and Spin Fluctuations in the Two-Dimensional Extended Hubbard Model: Extended Two-Particle Self-Consistent Approach
• Nearest-Neighbor Repulsion and Competing Charge and Spin Order in the Extended Hubbard Model
• Underdoped cuprates phenomenology in the 2D Hubbard model within COM(SCBA)
• Emery vs. Hubbard model for cuprate superconductors: a Composite Operator Method study
• Phase diagram of one-dimensional Hubbard-Holstein model at quarter-filling
• Composite Operator Method analysis of the underdoped cuprates puzzle
• The Hubbard model beyond the two-pole approximation: a Composite Operator Method study
• The Composite Operator Method (COM)
• The extended Hubbard model with attractive interactions
• Exact solution of the 1D Hubbard model with NN and NNN interactions in the narrow-band limit
• Exact solution of the 1D Hubbard model in the atomic limit with inter-site magnetic coupling
• Phase diagrams of half-filled 1D and 2D extended Hubbard model within COM
• The composite operator method route to the 2D Hubbard model and the cuprates
• Role of the attractive intersite interaction in the extended Hubbard model
• COM(3p) solution of the 2D Hubbard model: momentum resolved quantities