Multi-orbital simplified parquet equations for strongly correlated electrons

Abstract

We extend an approximation earlier developed by us for the single-impurity Anderson model to a full-size impurity solver for models of interacting electrons with multiple orbitals. The approximation is based on parquet equations simplified by separating small and large energy fluctuations justified in the critical region of a pole in the two-particle vertex. We show that an $l$-orbital model with most general interaction is described within this approximation by $4l^2\times 4l^2$ matrices and is Fermi liquid in the metallic phase. We explicitly calculate properties of a paramagnetic solution of a two-orbital Hubbard model with a Hund exchange and orbital splitting within the dynamical mean-field approximation. We trace the genesis of a metal-insulator transition induced by a crystal field and vanishing of the Kondo quasiparticle peak in strongly correlated orbitally asymmetric systems.

14 pages, 15 figures

References in corpus (7)

• The numerical renormalization group method for quantum impurity systems
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• High-spin to low-spin and orbital polarization transitions in multiorbital Mott systems
• Quantum phase transition in capacitively coupled double quantum dots
• Analytic impurity solver with the Kondo strong-coupling asymptotics
• Kondo behavior in the asymmetric Anderson model: Analytic approach
• A local moment approach to the degenerate Anderson impurity model

Cited by in corpus (4)

• Multiscale space-time ansatz for correlation functions of quantum systems based on quantics tensor trains
• Development of an efficient impurity solver in dynamical mean field theory for multi-band systems: The iterative perturbation theory combined with the parquet equations
• Simplification of the local full vertex in the impurity problem in DMFT and its applications for the nonlocal correlation
• Improvement of the simplification method for the local two-particle full-vertex towards precise frequency behavior