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The Similarity Renormalization Group (SRG) is investigated as a powerful yet practical method to modify nuclear potentials so as to reduce computational requirements for calculations of observables. The key feature of SRG transformations…

Nuclear Theory · Physics 2009-12-16 E. D. Jurgenson

We present a new ab-initio method that uses similarity renormalization group (SRG) techniques to continuously diagonalize nuclear many-body Hamiltonians. In contrast with applications of the SRG to two- and three-nucleon interactions in…

Nuclear Theory · Physics 2011-07-21 K. Tsukiyama , S. K. Bogner , A. Schwenk

A strong effort will be dedicated in the coming years to extend the reach of ab initio nuclear-structure calculations to heavy doubly open-shell nuclei. In order to do so, the most efficient strategies to incorporate dominant many-body…

Precise theoretical calculations of open-shell atomic systems are critical for extracting fundamental physics parameters from precision experiments. Here we present proof-of-principle calculations illustrating the effectiveness of the…

Atomic Physics · Physics 2022-12-19 G. Tenkila , V. Chand , T. Miyagi , H. Patel , S. R. Stroberg , R. F. Garcia Ruiz , J. D. Holt

Ab initio nuclear many-body frameworks require extensive computational resources, especially when targeting heavier nuclei. Importance-truncation (IT) techniques allow to significantly reduce the dimensionality of the problem by neglecting…

Nuclear Theory · Physics 2022-03-31 J. Hoppe , A. Tichai , M. Heinz , K. Hebeler , A. Schwenk

We introduce a novel \abinitio many-body method designed to compute the properties of nuclei in the continuum. This approach combines well-established techniques, namely the Complex Scaling (CS) and Similarity Renormalization Group (SRG)…

Nuclear Theory · Physics 2025-07-03 Osama Yaghi , Guillaume Hupin , Petr Navrátil

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

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

\textbf{Background} The reach of \textit{ab initio} theory has greatly increased in recent decades. However, predicting the location of the drip lines remains challenging due to uncertainties in nuclear forces and difficulties in describing…

Nuclear Theory · Physics 2026-01-23 A. Sehovic , K. Fossez , H. Hergert

We present two new methods for performing ab initio calculations of excited states for closed-shell systems within the in-medium similarity renormalization group (IMSRG) framework. Both are based on combining the IMSRG with simple many-body…

Nuclear Theory · Physics 2017-05-10 N. M. Parzuchowski , T. D. Morris , S. K. Bogner

We study the use of truncated normal-ordered three-nucleon interactions in ab initio nuclear structure calculations starting from chiral two- plus three-nucleon Hamiltonians evolved consistently with the similarity renormalization group…

Nuclear Theory · Physics 2012-09-05 Robert Roth , Sven Binder , Klaus Vobig , Angelo Calci , Joachim Langhammer , Petr Navratil

We use the newly developed Multi-Reference In-Medium Similarity Renormalization Group to study all even isotopes of the calcium and nickel isotopic chains, based on two- plus three-nucleon interactions derived from chiral effective field…

Nuclear Theory · Physics 2014-10-29 H. Hergert , S. K. Bogner , T. D. Morris , S. Binder , A. Calci , J. Langhammer , R. Roth

Resonance is a general phenomenon which can happen in classic or quantum systems. An unbound many-body quantum system can undergo a self-resonant process. It has long been a challenge how to describe unbound many-body quantum systems in…

Nuclear Theory · Physics 2020-01-23 B. S. Hu , Q. Wu , Z. H. Sun , F. R. Xu

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

Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain "magic" numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly-magic features are…

We present a nonperturbative derivation of effective valence-shell Hamiltonians in the framework of the recently developed in-medium similarity renormalization group (IM-SRG). As a first application, we calculate the spectra of $p$- and…

Nuclear Theory · Physics 2012-07-03 K. Tsukiyama , S. K. Bogner , A. Schwenk

Short-range correlations (SRCs) provide the link between low- and high-energy nuclear physics and can be quantified by two-nucleon densities. We present calculations of the two-nucleon densities using free-space similarity renormalization…

Nuclear Theory · Physics 2026-02-06 H. Y. Shang , R. Z. Hu , X. Y. Xu , Z. C. Xu , J. C. Pei , S. M. Wang

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

The first nonperturbative version of the multireference driven similarity renormalization group (MR-DSRG) theory [C. Li and F. A. Evangelista, J. Chem. Theory Comput. $\mathbf{11}$, 2097 (2015)] is introduced. The renormalization group…

Chemical Physics · Physics 2016-05-25 Chenyang Li , Francesco A. Evangelista

Symmetry-violating observables such as the nuclear anapole and Schiff moments provide sensitive probes of the fundamental symmetries of nature and physics beyond the Standard Model. Their interpretation has been hindered, however, by the…