Effective three-particle interactions in low-energy models for multiband systems

Abstract

We discuss different approximations for effective low-energy interactions in multi-band models for weakly correlated electrons. In the study of Fermi surface instabilities of the conduction band(s), the standard approximation consists only keeping those terms in the bare interactions that couple only to the conduction band(s), while corrections due to virtual excitations into bands away from the Fermi surface are typically neglected. Here, using a functional renormalization group approach, we present an improved truncation for the treatment of the effective interactions in the conduction band that keeps track of the generated three-particle interactions (six-point term) and hence allows one to include important aspects of these virtual interband excitations. Within a simplified two-patch treatment of the conduction band, we demonstrate that these corrections can have a rather strong effect in parts of the phase diagram by changing the critical scales for various orderings and the phase boundaries.

revised version, 16 pages, 13 figures

References in corpus (5)

• Magnetism, superconductivity, and pairing symmetry in Fe-based superconductors
• Funtional Renormalization Group Study of the Pairing Symmetry and Pairing Mechanism of the FeAs Based High Temperature Superconductors
• Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
• Origin of Gap Anisotropy in Spin Fluctuation Models of the Fe-pnictides
• The two-loop functional renormalization-group approach to the one- and two-dimensional Hubbard model

Cited by in corpus (9)

• Multiloop functional renormalization group for the two-dimensional Hubbard model: Loop convergence of the response functions
• Multiscale space-time ansatz for correlation functions of quantum systems based on quantics tensor trains
• Correlated starting points for the functional renormalization group
• Random Phase Approximation for gapped systems: role of vertex corrections and applicability of the constrained random phase approximation
• Truncated-Unity Parquet Equations: Application to the Repulsive Hubbard Model
• Effective interactions in multi-band systems from constrained summations
• Multiorbital effects in the functional renormalization group: A weak-coupling study of the Emery model
• Functional renormalization group study of an eight-band model for the iron arsenides
• Effective three particle forces in polyvalent atoms