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We study the limits of the energy resolution that can be achieved in the calculations of spectral functions of quantum impurity models using the numerical renormalization group (NRG) technique with interleaving (z-averaging). We show that…

Strongly Correlated Electrons · Physics 2009-03-05 Rok Zitko , Thomas Pruschke

The numerical renormalization group (NRG) is rephrased as a variational method with the cost function given by the sum of all the energies of the effective low-energy Hamiltonian. This allows to systematically improve the spectrum obtained…

Quantum Physics · Physics 2013-05-23 Iztok Pizorn , Frank Verstraete

Numerical renormalization group (NRG) calculations of quantum impurity models, based on a logarithmic discretization in energy of electronic or bosonic Hamiltonians, provide a powerful tool to describe physics involving widely separated…

Strongly Correlated Electrons · Physics 2009-11-13 Axel Freyn , Serge Florens

Local three- and four-point correlators yield important insight into strongly correlated systems and have many applications. However, the nonperturbative, accurate computation of multipoint correlators is challenging, particularly in the…

Strongly Correlated Electrons · Physics 2021-10-15 Seung-Sup B. Lee , Fabian B. Kugler , Jan von Delft

The non-perturbative {\it ab initio} calculations of infinite nuclear matter using In-Medium Similarity Renormalization Group (IMSRG) method is developed in this work, which enables calculations with chiral two and three-nucleon forces at…

Nuclear Theory · Physics 2025-02-27 Xin Zhen , Rongzhe Hu , Haoyu Shang , Jiawei Chen , Junchen Pei , Furong Xu

We use the numerical renormalization group method (NRG) to investigate a single-impurity Anderson model with a coupling of the impurity to a superconducting host. Analysis of the energy flow shows, in contrast to previous belief, that NRG…

Strongly Correlated Electrons · Physics 2015-05-13 Theresa Hecht , Andreas Weichselbaum , Jan von Delft , Ralf Bulla

In this paper we introduce a new approach for calculating dynamical properties within the numerical renormalization group. It is demonstrated that the method previously used fails for the Anderson impurity in a magnetic field due to the…

Strongly Correlated Electrons · Physics 2009-10-31 Walter Hofstetter

We review recent developments in the use of renormalization group (RG) methods in low-energy nuclear physics. These advances include enhanced RG technology, particularly for three-nucleon forces, which greatly extends the reach and accuracy…

Nuclear Theory · Physics 2013-11-14 R. J. Furnstahl , K. Hebeler

The Numerical Renormalization Group method (NRG) has been developed by Wilson in the 1970's to investigate the Kondo problem. The NRG allows the non-perturbative calculation of static and dynamic properties for a variety of impurity models.…

Strongly Correlated Electrons · Physics 2009-10-31 R. Bulla

Quantum impurity problems can be solved using the numerical renormalization group (NRG), which involves discretizing the free conduction electron system and mapping to a `Wilson chain'. It was shown recently that Wilson chains for different…

Strongly Correlated Electrons · Physics 2016-06-08 K. M. Stadler , A. K. Mitchell , J. von Delft , A. Weichselbaum

We present a new method to calculate directly the one-particle self-energy of an impurity Anderson model with Wilson's numerical Renormalization Group method by writing this quantity as the ratio of two correlation functions. This way of…

Strongly Correlated Electrons · Physics 2009-10-31 R. Bulla , A. C. Hewson , Th. Pruschke

A quantitative criterion to prove and analyze convergence within the numerical renormalization group (NRG) is introduced. By tracing out a few further NRG shells, the resulting reduced density matrices carry relevant information on…

Strongly Correlated Electrons · Physics 2015-03-19 Andreas Weichselbaum

The detection of gravitational waves has intensified the need for efficient, high-precision modeling of the two-body problem in General Relativity. Current analytical methods, primarily the Post-Minkowskian and Post-Newtonian expansions,…

General Relativity and Quantum Cosmology · Physics 2026-05-28 F. Gutiérrez , K. Falls , A. Codello

Numerical approaches are an important tool to study strongly correlated quantum systems. However, their fragility with respect to rounding errors is not well studied and numerically verified enclosures of the results are not available. In…

Strongly Correlated Electrons · Physics 2019-02-20 Peter Schmitteckert

We systematically study a numerical procedure that reveals the asymptotically self-similar dynamics of solutions of partial differential equations (PDEs). This procedure, based on the renormalization group (RG) theory for PDEs, appeared…

Numerical Analysis · Mathematics 2018-07-12 Gastão A. Braga , Federico C. Furtado , Vincenzo Isaia , Long Lee

Exploiting symmetries in the numerical renormalization group (NRG) method significantly enhances performance by improving accuracy, increasing computational speed, and optimizing memory efficiency. Published codes focus on continuous…

Strongly Correlated Electrons · Physics 2024-09-19 Aitor Calvo-Fernández , María Blanco-Rey , Asier Eiguren

We present a numerical implementation of the renormalization group (RG) for partial differential equations, constructing similarity solutions and travelling waves. We show that for a large class of well-localized initial conditions,…

chao-dyn · Physics 2009-10-22 Lin-Yuan Chen , Nigel Goldenfeld

Machine learning techniques have recently gained prominence in physics, yielding a host of new results and insights. One key concept is that of backpropagation, which computes the exact gradient of any output of a program with respect to…

Strongly Correlated Electrons · Physics 2022-04-06 Jonas B. Rigo , Andrew K. Mitchell

In the numerical renormalization group (NRG) calculations of the spectral functions of quantum impurity models, the results are affected by discretization and truncation errors. The discretization errors can be alleviated by averaging over…

Strongly Correlated Electrons · Physics 2011-11-15 Rok Zitko

Although substantial progress has been achieved in solving quantum impurity problems, the numerical renormalization group (NRG) method generally performs poorly when applied to quantum lattice systems in a real-space blocking form. The…

Strongly Correlated Electrons · Physics 2018-09-03 Li-Xiang Cen
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