Abstract
The in-medium similarity renormalization group (IMSRG) is a powerful and flexible many-body method to compute the structure of nuclei starting from nuclear forces. Recent developments have extended the IMSRG from its standard truncation at the normal-ordered two-body level, the IMSRG(2), to a precision approximation including normal-ordered three-body operators, the IMSRG(3)-N7. This improvement provides a more precise solution to the many-body problem and makes it possible to quantify many-body uncertainties in IMSRG calculations. We explore the structure of Ca44,48,52 using the IMSRG(3)-N7, focusing on understanding existing discrepancies of the IMSRG(2) to experimental results. We find a significantly better description of the first 2+ excitation energy of Ca48, improving the description of the shell closure at N=28. At the same time, we find that the IMSRG(3)-N7 corrections to charge radii do not resolve the systematic underprediction of the puzzling large charge radius difference between Ca52 and Ca48. We present estimates of many-body uncertainties of IMSRG(2) calculations applicable also to other systems based on the size extensivity of the method.
| Original language | English |
|---|---|
| Article number | 034311 |
| Journal | Physical Review C |
| Volume | 111 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2025 |
Funding
We thank Gaute Hagen, Jan Hoppe, Gustav Jansen, and Thomas Papenbrock for helpful discussions, Francesca Bonaiti for providing additional coupled-cluster values for , and Martin Hoferichter and Frederic Noël for pointing out the error in Ref. and benchmarking the correction described in Appendix . M.H. gratefully acknowledges the hospitality of the Argonne National Laboratory nuclear theory group in 2022. This work was supported in part by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 101020842), by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Projektnummer 279384907 – SFB 1245, by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research and Office of Nuclear Physics, Scientific Discovery through Advanced Computing (SciDAC) program (SciDAC-5 NUCLEI), by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy, by JST ERATO Grant No. JPMJER2304, Japan, and by the U.S. National Science Foundation Grant No PHY-2340834-01. This research used resources of the Oak Ridge Leadership Computing Facility located at Oak Ridge National Laboratory, which is supported by the Office of Science of the Department of Energy under contract No. DE-AC05-00OR22725. The authors gratefully acknowledge the Gauss Centre for Supercomputing e.V. for funding this project by providing computing time through the John von Neumann Institute for Computing (NIC) on the GCS Supercomputer JUWELS at Jülich Supercomputing Centre (JSC) and the computing time provided to them on the high-performance computer Lichtenberg II at TU Darmstadt, funded by the German Federal Ministry of Education and Research (BMBF) and the State of Hesse. This work has been partially supported by U.S. DOE Grant No. DE-FG02-13ER41967. ORNL is managed by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan .