Strong Coupling Approach for Strongly Correlated Electron Systems
نویسنده
چکیده
A perturbation theory scheme in terms of electron hopping which is based on the Wick’s theorem for Hubbard operators is developed. Diagrammatic series contain single-site vertices connected by hopping lines and it is shown that for each vertice the problem splits into the subspaces with “vacuum states” determined by the diagonal Hubbard operators and only excitations around these “vacuum states” are allowed. The rules to construct diagrams are proposed. In the limit of infinite spatial dimensions the total auxiliary single-site problem exactly splits into subspaces which allows to build an analytical thermodynamically consistent approach for Hubbard model. Some analytical results are given for simple approximations when 2-pole and 4-pole structure for Green’s function is obtained. 05.30.Fk, 71.10.Fd, 71.15.m, 71.27.+a Typeset using REVTEX
منابع مشابه
ابررسانای d- موجی، پادفرومغناطیس و مایع اسپینی در ابررساناهای آلی شبه دوبعدی
The self-energy-functional approach is a powerful many-body tool to investigate different broken symmetry phases of strongly correlated electron systems. We use the variational cluster perturbation theory (also called the variational cluster approximation) to investigate the interplay between the antiferromagnetism and d-wave superconductivity of κ-(ET)2 X conductors. These compounds are desc...
متن کاملFirst - and Second Order Phase Transitions in the Holstein - Hubbard Model
– We investigate metal-insulator transitions in the half-filled Holstein-Hubbard model as a function of the on-site electron-electron interaction U and the electron-phonon coupling g. We use several different numerical methods to calculate the phase diagram, the results of which are in excellent agreement. When the electron-electron interaction U is dominant the transition is to a Mott-insulato...
متن کاملDisorder screening in strongly correlated systems.
Electron-electron interactions generally reduce the low temperature resistivity due to the screening of the impurity potential by the electron gas. In the weak-coupling limit, the magnitude of this screening effect is determined by the thermodynamic compressibility which is proportional to the inverse screening length. We show that when strong correlations are present, although the compressibil...
متن کاملExchange coupling in quantum rings and wires in the Wigner-crystal limit
We present a controlled method for computing the exchange coupling in strongly correlated onedimensional electron systems. The asymptotically exact relation between the exchange constant and the pair-correlation function of spinless electrons is derived. Explicit results are obtained for thin quantum rings with realistic Coulomb interactions, by calculating this function via a many-body instant...
متن کاملKondo insulators in the periodic Anderson model: a local moment approach
The symmetric periodic Anderson model is well known to capture the essential physics of Kondo insulator materials. Within the framework of dynamical mean-field theory, we develop a local moment approach to its single-particle dynamics in the paramagnetic phase. The approach is intrinsically nonperturbative, encompasses all energy scales and interaction strengths, and satisfies the low-energy di...
متن کاملSurprises in Correlated Electron Physics
The exceptional properties of strongly correlated electron systems have fascinated physicists for several decades already [1–9]. New correlated electron materials and unexpected correlation phenomena are discovered every year. Often the properties of those systems are influenced by disorder. Unfortunately, real materials and even model systems with strong electronic correlations and disorder ar...
متن کامل