Sum rule violation in self-consistent hybridization expansions

Article

关键词: MEAN-FIELD THEORY;    QUANTUM IMPURITY MODELS;    PERTURBATION-THEORY;    ANDERSON MODEL;    HUBBARD-MODEL;    ELECTRONIC-STRUCTURE;    INFINITE DIMENSIONS;    SYSTEMS;    APPROXIMATION;    LIMIT;   

DOI  :  10.1103/PhysRevB.87.075124

来源: SCIE

【 摘 要 】

We show that for multiorbital quantum impurity models the noncrossing approximation and one-crossing approximation versions of the self-consistent hybridization expansions violate the sum rules relating the coefficients of the high-frequency expansion of the self-energy and the product of the self-energy and Green's function to thermodynamic expectation values. Comparison of noncrossing/one-crossing results to numerically exact quantum Monte Carlo calculations shows that the consistency with sum rules provides a useful estimate of the reliability of the approximations. The sum rule violations are more pronounced, and therefore the quality of the noncrossing/one-crossing approximation is poorer, in situations with multiple orbitals and away from particle-hole symmetry but becomes less severe as the correlation strength increases. The one-crossing approximation is markedly superior to the noncrossing approximation. DOI: 10.1103/PhysRevB.87.075124

【 授权许可】

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