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The Density Matrix Renormalization Group (DMRG) has become a powerful numerical method that can be applied to low-dimensional strongly correlated fermionic and bosonic systems. It allows for a very precise calculation of static, dynamical…

Condensed Matter · Physics 2007-05-23 Karen Hallberg

We present a new hybrid multiconfigurational method based on the concept of range-separation that combines the density matrix renormalization group approach with density functional theory. This new method is designed for the simultaneous…

An active space variational calculation of the 2-electron reduced density matrix (2-RDM) is derived and implemented where the active orbitals are correlated within the pair approximation. The pair approximation considers only doubly…

Chemical Physics · Physics 2020-10-13 Kade Head-Marsden , David A. Mazziotti

We report the derivation and implementation of orbital optimization algorithms for the active space decomposition (ASD) model, which are extensions of complete active space self-consistent field (CASSCF) and its occupation-restricted…

Chemical Physics · Physics 2015-08-17 Inkoo Kim , Shane M. Parker , Toru Shiozaki

Layers of two-dimensional materials arranged at a twist angle with respect to each other lead to enlarged unit cells with potentially strongly altered band structures, offering a new arena for novel and engineered many-body ground states.…

Strongly Correlated Electrons · Physics 2020-08-18 Lennart Klebl , Dante M. Kennes , Carsten Honerkamp

An efficient density matrix renormalization group (DMRG) algorithm is presented for the Bethe lattice with connectivity $Z = 3$ and antiferromagnetic exchange between nearest neighbor spins $s= 1/2$ or 1 sites in successive generations $g$.…

Strongly Correlated Electrons · Physics 2015-06-03 Manoranjan Kumar , S. Ramasesha , Zoltan G. Soos

The Density Matrix Renormalization Group (DMRG) has become a powerful numerical method that can be applied to low-dimensional strongly correlated fermionic and bosonic systems. It allows for a very precise calculation of static, dynamic and…

Condensed Matter · Physics 2007-05-23 Karen Hallberg

Systems of Y-junctions are interesting both from a fundamental viewpoint and because of their potential use in nanoscale devices. These systems can be studied numerically with the density matrix renormalization group(DMRG), but existing…

Strongly Correlated Electrons · Physics 2007-05-23 Haihui Guo , Steven R. White

We summarize our recent efforts to develop the Density Matrix Renormalization Group (DMRG) method into a practical truncation strategy for large-scale nuclear shell model calculations. Following an overview of the essential features of the…

Nuclear Theory · Physics 2009-04-16 S. Pittel , B. Thakur

We describe the use of the Density Matrix Renormalization Group method as a means of approximately solving large-scale nuclear shell-model problems. We focus on an angular-momentum-conserving variant of the method and report test results…

Nuclear Theory · Physics 2011-05-12 S. Pittel , N. Sandulescu

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

We propose a second renormalization group method to handle the tensor-network states or models. This method reduces dramatically the truncation error of the tensor renormalization group. It allows physical quantities of classical…

Strongly Correlated Electrons · Physics 2024-06-26 Z. Y. Xie , H. C. Jiang , Q. N. Chen , Z. Y. Weng , T. Xiang

We present an alternative, memory-efficient, Schmidt decomposition-based description of the inherently bipartite restricted active space (RAS) scheme, which can be implemented effortlessly within the density matrix renormalization group…

The Density Matrix Renormalization Group (DMRG) method has become a prominent tool for simulating strongly correlated electronic systems characterized by dominant static correlation effects. However, capturing the full scope of electronic…

Chemical Physics · Physics 2024-11-13 Nicholas Bauman , Libor Veis , Karol Kowalski , Jiri Brabec

The functional renormalization group method is used to take into account the vacuum polarization around localized bound states generated by external potential. The application to Atomic Physics leads to improved Hartree-Fock and Kohn-Sham…

Strongly Correlated Electrons · Physics 2007-05-23 Janos Polonyi

We propose a density matrix renormalization group approach to tackle a two-state system coupled to a bosonic bath with continuous spectrum. In this approach, the optimized phonon scheme is applied to several hundred phonon modes which are…

Strongly Correlated Electrons · Physics 2008-05-31 Hang Wong , Zhi-De Chen

A new efficient numerical algorithm for interacting fermion systems is proposed and examined in detail. The ground state is expressed approximately by a linear combination of numerically chosen basis states in a truncated Hilbert space. Two…

Strongly Correlated Electrons · Physics 2007-05-23 Tsuyoshi Kashima , Masatoshi Imada

We implement an adaptive mesh algorithm for calculating the space and time dependence of the atomic density field during materials processing. Our numerical approach uses the systematic renormalization-group formulation of the phase field…

There has been recent interest in the deployment of ab initio density matrix renormalization group computations on high performance computing platforms. Here, we introduce a reformulation of the conventional distributed memory ab initio…

Chemical Physics · Physics 2021-06-24 Huanchen Zhai , Garnet Kin-Lic Chan

I apply a two-step density-matrix renormalization group method to the anisotropic two-dimensional tight-binding model. This study, which is a prelude to the study of models of quasi-one dimensional materials, shows the potential power of…

Strongly Correlated Electrons · Physics 2013-05-29 S. Moukouri