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In previous work we have shown that the Density Matrix Renormalization Group (DMRG) enables near-exact calculations in active spaces much larger than are possible with traditional Complete Active Space algorithms. Here, we implement orbital…

Strongly Correlated Electrons · Physics 2009-11-13 Debashree Ghosh , Johannes Hachmann , Takeshi Yanai , Garnet K. -L. Chan

Strong-Disorder Renormalization Group (SDRG), despite being a relatively simple real-space renormalization procedure, provides in principle exact results on the critical properties at the infinite-randomness fixed point of random quantum…

Statistical Mechanics · Physics 2020-01-29 Christophe Chatelain

We show Poisson statistics for random band matrices which diagonal entries have Gaussian components. These components are possibly as small as $n^{-\varepsilon}$. Particularly, our result is applicable for a band matrix cut from the GUE…

Mathematical Physics · Physics 2015-06-02 Vladimir Pchelin

We present a rotationally invariant matrix product method (MPM) of isotropic spin chains. This allows us to deal with a larger number of variational MPM parameters than those considered earlier by other authors. We also show the relation…

Strongly Correlated Electrons · Physics 2009-10-30 J. Dukelsky , M. A. Martin-Delgado , T. Nishino , G. Sierra

We describe a low cost alternative to the standard variational DMRG (density matrix renormalization group) algorithm that is analogous to the combination of selected configuration interaction plus perturbation theory (SCI+PT). We denote the…

Chemical Physics · Physics 2018-03-28 Sheng Guo , Zhendong Li , Garnet Kin-Lic Chan

In a recent Letter [Phys. Rev. Lett. 88, 256403(2002), cond-mat/0109158] Cazalilla and Marston proposed a time-dependent density- matrix renormalization group (TdDMRG) algorithm for the accurate evaluation of out-of-equilibrium properties…

Strongly Correlated Electrons · Physics 2007-05-23 H. G. Luo , T. Xiang , X. Q. Wang

The density matrix renormalization group (DMRG) approach is extended to complex-symmetric density matrices characteristic of many-body open quantum systems. Within the continuum shell model, we investigate the interplay between many-body…

Nuclear Theory · Physics 2009-11-11 J. Rotureau , N. Michel , W. Nazarewicz , M. Ploszajczak , J. Dukelsky

We use the density matrix renormalization group (DMRG) to perform a detailed study of the critical properties of the two dimensional Q state Potts model, including the magnetization and energy-density profiles, bulk and surface critical…

Condensed Matter · Physics 2009-10-30 Enrico Carlon , Ferenc Igloi

We present an implementation of the relativistic quantum-chemical density matrix renormalization group (DMRG) approach based on a matrix-product formalism. Our approach allows us to optimize matrix product state (MPS) wave functions…

Chemical Physics · Physics 2017-10-24 Stefano Battaglia , Sebastian Keller , Stefan Knecht

We present an efficient implementation of the Density Matrix Renormalization Group (DMRG) algorithm that includes an optimal ordering of the proton and neutron orbitals and an efficient expansion of the active space utilizing various…

Nuclear Theory · Physics 2015-11-18 Ö. Legeza , L. Veis , A. Poves , J. Dukelsky

Nematic order is an exotic property observed in several strongly correlated systems, such as the iron-based superconductors. Using large-scale density matrix renormalization group (DMRG) techniques, we study at zero-temperature the nematic…

Strongly Correlated Electrons · Physics 2020-01-16 Wen-Jun Hu , Shou-Shu Gong , Hsin-Hua Lai , Qimiao Si , Elbio Dagotto

For a prototype quadratic Hamiltonian describing a driven, dissipative system, exact matrix elements of the reduced density matrix are obtained from a generating function in terms of the normal characteristic functions. The approach is…

Quantum Physics · Physics 2021-08-24 Sh. Saedi , F. Kheirandish

We implement and apply time-dependent density matrix renormalization group (TD-DMRG) algorithms at zero and finite temperature to compute the linear absorption and fluorescence spectra of molecular aggregates. Our implementation is within a…

Chemical Physics · Physics 2019-07-30 Jiajun Ren , Zhigang Shuai , Garnet Kin-Lic Chan

We show that spin and fermion representations for solvable quantum chains lead in general to different reduced density matrices if the subsystem is not singly connected. We study the effect for two sites in XX and XY chains as well as for…

Statistical Mechanics · Physics 2015-05-14 Ferenc Igloi , Ingo Peschel

We extend the density matrix renormalization group to compute exact ground states of continuum many-electron systems in one dimension with long-range interactions. We find the exact ground state of a chain of 100 strongly correlated…

Strongly Correlated Electrons · Physics 2012-08-06 E. M. Stoudenmire , Lucas O. Wagner , Steven R. White , Kieron Burke

We develop the Density Matrix Renormalization Group (DMRG) technique for numerically studying incompressible fractional quantum Hall (FQH) states on the sphere. We calculate accurate estimates for ground state energies and excitationgaps at…

Mesoscale and Nanoscale Physics · Physics 2009-07-21 A. E. Feiguin , E. Rezayi , C. Nayak , S. Das Sarma

We propose two estimators of a monotone spectral density, that are based on the periodogram. These are the isotonic regression of the periodogram and the isotonic regression of the log-periodogram. We derive pointwise limit distribution…

Statistics Theory · Mathematics 2011-03-10 Dragi Anevski , Philippe Soulier

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 study the spectral properties of a class of random matrices where the matrix elements depend exponentially on the distance between uniformly and randomly distributed points. This model arises naturally in various physical contexts, such…

Disordered Systems and Neural Networks · Physics 2015-05-18 Ariel Amir , Yuval Oreg , Yoseph Imry

In this paper we describe how the density matrix renormalization group (DMRG) can be used for quantum chemical calculations for molecules, as an alternative to traditional methods, such as configuration interaction or coupled cluster…

Condensed Matter · Physics 2009-10-31 Steven R. White , Richard L. Martin