Abstract
Efforts to describe nuclear structure and dynamics from first principles have advanced significantly in recent years. Exact methods for light nuclei are now able to include continuum degrees of freedom and treat structure and reactions on the same footing, and multiple approximate, computationally efficient many-body methods have been developed that can be routinely applied for medium-mass nuclei. This has made it possible to confront modern nuclear interactions from Chiral Effective Field Theory, that are rooted in Quantum Chromodynamics with a wealth of experimental data.Here, we discuss one of these efficient new many-body methods, the In-Medium Similarity Renormalization Group (IMSRG), and its applications in modern nuclear structure theory. The IMSRG evolves the nuclear many-body Hamiltonian in second-quantized form through continuous unitary transformations that can be implemented with polynomial computational effort. Through suitably chosen generators, we drive the matrix representation of the Hamiltonian in configuration space to specific shapes, e.g., to implement a decoupling of low-and high-energy scales, or to extract energy eigenvalues for a given nucleus.We present selected results from Multireference IMSRG (MR-IMSRG) calculations of open-shell nuclei, as well as proof-of-principle applications for intrinsically deformed medium-mass nuclei. We discuss the successes and prospects of merging the (MR-)IMSRG with many-body methods ranging from Configuration Interaction to the Density Matrix Renormalization Group, with the goal of achieving an efficient simultaneous description of dynamic and static correlationsin atomic nuclei.
Highlights
Effective Field Theory (EFT) and Renormalization Group (RG) methods have become important tools of modern many-body theory
We present selected results from Multireference In-Medium Similarity Renormalization Group (IMSRG) (MR-IMSRG) calculations of openshell nuclei, as well as proof-of-principle applications for intrinsically deformed medium-mass nuclei
We show that the same improvement is found for all even oxygen isotopes, which is very promising for future applications of the approximate merging the (MR-)IMSRG(3) in general open-shell nuclei
Summary
Effective Field Theory (EFT) and Renormalization Group (RG) methods have become important tools of modern (nuclear) many-body theory. If we consider applying this idea in genuine manybody systems like medium-mass or heavy nuclei, we quickly realize that an SRG evolution of the many-body Hamiltonian matrix would be a very inefficient approach for solving the Schrodinger equation, because the RHS of Eq (3) forces us to repeatedly perform products of matrices whose dimension grows factorially with the number of particles and single-particle basis states. We note that due to the normal ordering, the zero-, one-, and two-body coefficients all contain in-medium contributions from the threebody interaction, i.e., contractions of three-body matrix elements with the density matrices of the reference state This explains the name In-Medium SRG, and will play an important role when we introduce truncations of the IMSRG flow equations below.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
