Two-site dynamical mean-field theory

Article

关键词: HUBBARD-MODEL;    MOTT TRANSITION;    INFINITE DIMENSIONS;    ELECTRON CORRELATION;    SELF-ENERGY;    FERROMAGNETISM;    INSULATOR;    MAGNETISM;    FERMIONS;    SYSTEMS;   

DOI  :  10.1103/PhysRevB.64.165114

来源: SCIE

【 摘 要 】

It is shown that a minimum realization of the dynamical mean-field theory (DMFT) can be achieved by mapping a correlated lattice model onto an impurity model in which the impurity is coupled to an uncorrelated bath that consists of a single site only. The two-site impurity model can be solved exactly. The mapping is approximate, The self-consistency conditions are constructed in a way that the resulting two-site DMFT reduces to the previously discussed linearized DMFT for the Mott transition. It is demonstrated that a reasonable description of the mean-field physics is possible with a minimum computational effort. This qualifies the simple two-site DMFT for a systematic study of more complex lattice models which cannot be treated by the full DMFT in a feasible way. To show the strengths and limitations of the new approach, the single-band Hubbard model is investigated in detail. The predictions of the two-site DMFT are compared with results of the full DMFT. Internal consistency checks are performed which concern the Luttinger sum rule, other Fermi-liquid relations and thermodynamic consistency.

【 授权许可】

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