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The recently proposed combination of the valence-space in-medium similarity renormalization group (VS-IMSRG) with the density matrix renormalization group (DMRG) offers a scalable and flexible many-body approach for strongly correlated…

Nuclear Theory · Physics 2024-08-12 A. Tichai , K. Kapás , T. Miyagi , M. A. Werner , Ö. Legeza , A. Schwenk , G. Zarand

We discuss the problem of estimating Radon-Nikodym derivatives. This problem appears in various applications, such as covariate shift adaptation, likelihood-ratio testing, mutual information estimation, and conditional probability…

Statistics Theory · Mathematics 2023-08-16 Duc Hoan Nguyen , Werner Zellinger , Sergei V. Pereverzyev

We reconsider the problem of calculating a general spectral correlation function containing an arbitrary number of products and ratios of characteristic polynomials for a N x N random matrix taken from the Gaussian Unitary Ensemble (GUE).…

Mathematical Physics · Physics 2015-06-26 Yan V Fyodorov , Eugene Strahov

We present a method for computing resonant inelastic x-ray scattering (RIXS) spectra in one-dimensional systems using the density matrix renormalization group (DMRG) method. By using DMRG to address the problem, we shift the computational…

Strongly Correlated Electrons · Physics 2018-09-20 A. Nocera , U. Kumar , N. Kaushal , G. Alvarez , E. Dagotto , S. Johnston

We propose a simple modification of the density matrix renormalization group (DMRG) method in order to tackle strongly disordered quantum spin chains. Our proposal, akin to the idea of the adaptive time-dependent DMRG, enables us to reach…

Strongly Correlated Electrons · Physics 2018-11-14 J. C. Xavier , J. A. Hoyos , E. Miranda

We adapt White's density matrix renormalisation group (DMRG) to the direct study of critical phenomena. We use the DMRG to generate transformations in the space of coupling constants. We postulate that a study of density matrix eigenvalues…

Condensed Matter · Physics 2007-05-23 R. J. Bursill , F. Gode

In this article we wish to present a new method to obtain spectral functions at finite temperature and density from the Functional Renormalization Group (FRG). The FRG offers a powerful non-perturbative tool to deal with phase transitions…

High Energy Physics - Phenomenology · Physics 2014-09-17 Jochen Wambach , Ralf-Arno Tripolt , Nils Strodthoff , Lorenz von Smekal

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

Variational approaches for the calculation of vibrational wave functions and energies are a natural route to obtain highly accurate results with controllable errors. However, the unfavorable scaling and the resulting high computational cost…

Chemical Physics · Physics 2017-08-14 Alberto Baiardi , Christopher J. Stein , Vincenzo Barone , Markus Reiher

We show that the numerical renormalization group (NRG) is a viable multi-band impurity solver for Dynamical Mean Field Theory (DMFT), offering unprecedent real-frequency spectral resolution at arbitrarily low energies and temperatures. We…

Strongly Correlated Electrons · Physics 2015-09-30 K. M. Stadler , A. Weichselbaum , Z. P. Yin , J. von Delft , G. Kotliar

The particle-hole Density Matrix Renormalization Group (p-h DMRG) method is discussed as a possible new approach to large-scale nuclear shell-model calculations. Following a general description of the method, we apply it to a class of…

Nuclear Theory · Physics 2011-05-12 J. Dukelsky , S. Pittel , S. S. Dimitrova , M. V. Stoitsov

We generalize the spectral sum rule preserving density matrix numerical renormalization group (DM-NRG) method in such a way that it can make use of an arbitrary number of not necessarily Abelian, local symmetries present in the quantum…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 A. I. Toth , C. P. Moca , O. Legeza , G. Zarand

The nonrelativistic reduction of the self-consistent covariant density functional theory is realized for the first time with the similarity renormalization group (SRG) method. The reduced nonrelativistic Hamiltonian and densities are…

Nuclear Theory · Physics 2020-08-19 Z. X. Ren , P. W. Zhao

Wilson's Numerical Renormalization Group (NRG) is so far the only nonperturbative technique that can reliably access low-energy properties of quantum impurity systems. We present a recent extension of the method, the DM-NRG, which yields…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Walter Hofstetter

Density matrix renormalization group (DMRG) is one of the most powerful numerical methods available for many-body systems. In this work, we develop a perturbation theory of DMRG (PT-DMRG) to largely increase its accuracy in an extremely…

Strongly Correlated Electrons · Physics 2017-03-01 Emanuele Tirrito , Shi-Ju Ran , Andrew J. Ferris , Ian P. McCulloch , Maciej Lewenstein

We propose a real-space renormalization group algorithm for accurately coarse-graining two-dimensional tensor networks. The central innovation of our method lies in utilizing variational boundary tensors as a globally optimized environment…

Statistical Mechanics · Physics 2026-03-03 Feng-Feng Song , Naoki Kawashima

We present a numerical method for calculating piecewise smooth spectral functions of correlated quantum systems in the thermodynamic limit from the spectra of finite systems computed using the dynamical or correction-vector density-matrix…

Strongly Correlated Electrons · Physics 2014-05-05 Martin Paech , Eric Jeckelmann

The density-matrix renormalization group (DMRG) is a numerical algorithm for the efficient truncation of the Hilbert space of low-dimensional strongly correlated quantum systems based on a rather general decimation prescription. This…

Strongly Correlated Electrons · Physics 2009-11-10 Ulrich Schollwoeck

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

We introduce the density matrix renormalization group (DMRG) method as an efficient computational tool for one-exciton approximations with off-diagonal disorder. This method allows us to reduce the computational effort by targetting only a…

Strongly Correlated Electrons · Physics 2007-05-23 M. A. Martin-Delgado , J. Rodriguez-Laguna , G. Sierra