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The conceptual framework provided by the functional Renormalization Group (fRG) has become a formidable tool to study correlated electron systems on lattices which, in turn, provided great insights to our understanding of complex many-body…

Computational Engineering, Finance, and Science · Computer Science 2016-11-02 Julian Lichtenstein , Jan Winkelmann , David Sánchez de la Peña , Toni Vidović , Edoardo Di Napoli

The functional renormalisation group (fRG) has evolved into a versatile tool in condensed matter theory for studying important aspects of correlated electron systems. Practical applications of the method often involve a high numerical…

Computational Physics · Physics 2016-09-21 Daniel Rohe

We derive an expansion of the functional renormalization (fRG) equations that treats the frequency and momentum dependencies of the vertices in a systematic manner. The scheme extends the channel-decomposed fRG equations to the frequency…

Strongly Correlated Electrons · Physics 2021-07-07 Nahom K. Yirga , David K. Campbell

The functional renormalization group (fRG) is an established tool in the treatment of correlated electron systems, notably for the description of competing instabilities. In recent years, methodological advancements led to the multiloop…

Strongly Correlated Electrons · Physics 2025-12-15 Kilian Fraboulet , Aiman Al-Eryani , Sarah Heinzelmann , Anna Kauch , Sabine Andergassen

We present the SpinParser open-source software [ https://github.com/fbuessen/SpinParser ]. The software is designed to perform pseudofermion functional renormalization group (pf-FRG) calculations for frustrated quantum magnets in two and…

Computational Physics · Physics 2022-09-02 Finn Lasse Buessen

We introduce DiFfRG (Discretisation Framework for functional Renormalisation Group flows), a comprehensive computational C++ framework for solving functional Renormalisation Group flows in very general truncation schemes. Its central…

High Energy Physics - Phenomenology · Physics 2024-12-18 Franz R. Sattler , Jan M. Pawlowski

We investigate the functional renormalization group (FRG) flow of the two-particle vertex function of a model for X-ray absorption in metals. Concerning the appearance of logarithmic divergences, the model is prototypical for an important…

Strongly Correlated Electrons · Physics 2021-05-03 Jan Diekmann , Severin G. Jakobs

We present the first calculation of fermion spectral function at finite temperature in quark-meson model in the framework of the functional renormalization group (FRG). We compare the results in two truncations, after first evolving flow…

High Energy Physics - Phenomenology · Physics 2018-12-05 Ziyue Wang , Lianyi He

This paper provides a study and discussion of earlier as well as novel more efficient schemes for the precise evaluation of finite-temperature response functions of strongly correlated quantum systems in the framework of the time-dependent…

Quantum Physics · Physics 2013-07-19 Thomas Barthel

First-order phase transitions in many-fermion systems are not detected in the susceptibility analysis of common renormalization-group (RG) approaches. Here we introduce a counterterm technique within the functional renormalization-group…

Strongly Correlated Electrons · Physics 2007-05-23 R. Gersch , J. Reiss , C. Honerkamp

The renormalization group plays an essential role in many areas of physics, both conceptually and as a practical tool to determine the long-distance low-energy properties of many systems on the one hand and on the other hand search for…

Statistical Mechanics · Physics 2021-05-10 N. Dupuis , L. Canet , A. Eichhorn , W. Metzner , J. M. Pawlowski , M. Tissier , N. Wschebor

In this paper, we report mean-field and effective-field renormalization group calculations on the isotropic Heisenberg antiferromagnetic model under a longitudinal magnetic field. As is already known, these methods, denoted by MFRG and…

Statistical Mechanics · Physics 2018-12-26 Minos A. Neto , J. Roberto Viana , Octavio D. R. Salmon , E. Bublitz Filho , J. Ricardo de Sousa

We present an alternative functional renormalization group (fRG) approach to the single-impurity Anderson model at finite temperatures. Starting with the exact self-energy and interaction vertex of a small system ('core') containing a…

Strongly Correlated Electrons · Physics 2013-01-11 Michael Kinza , Jutta Ortloff , Johannes Bauer , Carsten Honerkamp

The functional renormalization group (FRG) provides a flexible tool to study correlations in low-dimensional electronic systems. In this paper, we present a novel FRG approach to the steady-state of quantum wires out of thermal equilibrium.…

Strongly Correlated Electrons · Physics 2020-12-08 Christian Klöckner , Dante Marvin Kennes , Christoph Karrasch

The pseudo-fermion functional renormalization group is generalized to treat spin Hamiltonians with finite magnetic fields, enabling its application to arbitrary spin lattice models with linear and bilinear terms in the spin operators. We…

Strongly Correlated Electrons · Physics 2025-01-30 Vincent Noculak , Johannes Reuther

We analyze a variety of integration schemes for the momentum space functional renormalization group calculation with the goal of finding an optimized scheme. Using the square lattice $t-t'$ Hubbard model as a testbed we define and benchmark…

Strongly Correlated Electrons · Physics 2023-01-27 Jacob Beyer , Florian Goth , Tobias Müller

We study the phase diagram of the antiferromagnetic $J_1$-$J_2$ Heisenberg model on the pyrochlore lattice with $S=1$ spins at zero and finite temperatures. We use a combination of complementary state-of-the-art quantum many-body approaches…

Strongly Correlated Electrons · Physics 2025-05-28 Imre Hagymási , Nils Niggemann , Johannes Reuther

We present a multiloop flow equation for the four-point vertex in the functional renormalization group (fRG) framework. The multiloop flow consists of successive one-loop calculations and sums up all parquet diagrams to arbitrary order.…

Strongly Correlated Electrons · Physics 2018-02-15 Fabian B. Kugler , Jan von Delft

We explore the possibilities of using the fermionic functional renormalization group to compute the phase diagram of systems with competing instabilities. In order to overcome the ubiquituous divergences encountered in RG flows, we propose…

Strongly Correlated Electrons · Physics 2009-11-30 M. Ossadnik , C. Honerkamp

The functional renormalization group (FRG) has been used widely to investigate phase diagrams, in particular the one of the two-dimensional Hubbard model. So far, the study of one-dimensional models has not attracted as much attention. We…

Strongly Correlated Electrons · Physics 2018-06-18 Lisa Markhof , Björn Sbierski , Volker Meden , Christoph Karrasch