Novel NN interaction and the spectroscopy of light nuclei

Shirokov, A. M.; Vary, James P.; Mazur, A. I.; Zaytsev, S. A.; Weber, Thomas A.

doi:10.1016/j.physletb.2005.06.043

Cited by 80 publications

(126 citation statements)

References 26 publications

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“…An absolute energy difference of 3 MeV between the IMSRG+SM and IMSRG(2) results is well within the realm of possibility, given the estimated uncertainties due to the many-body truncation. This is especially relevant because 28 Si is an N = Z nucleus, and therefore exhibits α-cluster correlations in excited states [196]. The IMSRG(2) energy contains only limited contributions from 4p4h excitations, which appear first as …”

Section: Deformation and Rotational Bandsmentioning

confidence: 99%

In-medium similarity renormalization group for closed and open-shell nuclei

Hergert¹

2016

Phys. Scr.

145

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Abstract. We present a pedagogical introduction to the In-Medium Similarity Renormalization Group (IMSRG) framework for ab initio calculations of nuclei. The IMSRG performs continuous unitary transformations of the nuclear many-body Hamiltonian in second-quantized form, which can be implemented with polynomial computational effort. Through suitably chosen generators, it is possible to extract eigenvalues of the Hamiltonian in a given nucleus, or drive the Hamiltonian matrix in configuration space to specific structures, e.g., band-or block-diagonal form.Exploiting this flexibility, we describe two complementary approaches for the description of closed-and open-shell nuclei: The first is the Multireference IMSRG (MR-IMSRG), which is designed for the efficient calculation of nuclear ground-state properties. The second is the derivation of nonempirical valence-space interactions that can be used as input for nuclear Shell model (i.e., configuration interaction (CI)) calculations. This IMSRG+Shell model approach provides immediate access to excitation spectra, transitions, etc., but is limited in applicability by the factorial cost of the CI calculations.We review applications of the MR-IMSRG and IMSRG+Shell model approaches to the calculation of ground-state properties for the oxygen, calcium, and nickel isotopic chains or the spectroscopy of nuclei in the lower sd shell, respectively, and present selected new results, e.g., for the ground-and excited state properties of neon isotopes.Submitted to: Phys. Scr.

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Section: Deformation and Rotational Bandsmentioning

confidence: 99%

In-medium similarity renormalization group for closed and open-shell nuclei

Hergert¹

2016

Phys. Scr.

145

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“…To achieve this, we form a union of two recent techniques -the J-matrix inverse scattering [4,5,6] and the NCSM [1]. A major ingredient of our approach is the form of the N N interaction (a small matrix in the oscillator basis), which is chosen to provide rapid convergence of manybody observables within the NCSM.…”

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confidence: 99%

“…We start from the realistic charge-independent N N interaction JISP6 [6] that provides an excellent description of the deuteron properties [6] and N N scattering data with χ 2 /datum = 1.03 for the 1992 np data base (2514 data), and 1.05 for the 1999 np data base (3058 data) [14]. JISP6 provides also a very good description of the spectra of p shell nuclei, but we find that it overbinds nuclei with A ≥ 10.…”

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confidence: 99%

Realistic nuclear Hamiltonian: Ab exitu approach

et al. 2007

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Fully-microscopic No-core Shell Model (NCSM) calculations of all stable s and p shell nuclei are used to determine a realistic N N interaction, JISP16, describing not only the two-nucleon data but the binding energies and spectra of nuclei with A ≤ 16 as well. The JISP16 interaction, providing rapid convergence of the NCSM calculations, is obtained in an ab exitu approach by phase-equivalent transformations of the JISP6 N N interaction. To complement the successful but computationally intensive 'ab initio' No-core Shell Model (NCSM) [1], we introduce the 'ab exitu' NCSM. While the former has proven very successful for light nuclei when one includes three-body (N N N ) forces [2,3], the computational complexity motivates us to introduce an approach that simultaneously minimizes N N N forces while providing more rapid convergence with a pure nucleon-nucleon (N N ) force. We invoke directly an end-goal of nuclear theory (hence the term 'ab exitu'), a successful description of nuclear properties, including the available N N data, to develop a new class of N N potentials that provide accurate descriptions of a broad range of nuclear data. PACSTo achieve this, we form a union of two recent techniques -the J-matrix inverse scattering [4,5,6] and the NCSM [1]. A major ingredient of our approach is the form of the N N interaction (a small matrix in the oscillator basis), which is chosen to provide rapid convergence of manybody observables within the NCSM. Indeed, we show below that results up through A = 16 obtained directly with the bare interaction (one that accurately describes the N N data) are close to those obtained with the effective interaction and are very useful to establish the confidence region for the binding energy.Since this is a departure from the more traditional approach, we motivate our development with observations concerning the successful ab initio approaches to light nuclei. Indeed several promising microscopic approaches have been introduced and tested extensively with realistic N N interactions (see [7] and references therein) and with realistic N N + N N N interactions [8,2,3]. Progress towards heavier nuclei appears limited only by scientific manpower and by available computers. However, all approaches face the exponentially rising computational complexity inherent in the quantum many-body problem with increasing particle number and novel schemes are needed to minimize the computational burden without sacrificing realism and precision.The earliest and most successful in reaching nuclei beyond A = 4 is the Green's-function Monte Carlo (GFMC) approach [8] whose power has been used to determine a sequence of everimproving N N N interactions [8,9,10], in conjunction with highly precise N N interactions [11] that 1

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“…However, the JISP16 saturation point is still overbound at too high a density as compared to conventional extrapolations to the infinite mass limit of heavy nuclei properties. The main idea of the JISP-type interaction is to utilize an ab exitu approach [1,39,40] in the N N force design, i. e., first the J-matrix inverse scattering approach [3] is used to construct an N N interaction perfectly describing the two-nucleon data (deuteron properties and N N scattering), next the interaction is modified by phase-equivalent transformations in order to achieve a reasonable description of many-body nuclear systems. Following this route, the JISP6 interaction fitted to nuclei with A ≤ 6 was proposed in Refs.…”

mentioning

confidence: 99%

“…Following this route, the JISP6 interaction fitted to nuclei with A ≤ 6 was proposed in Refs. [39,40]. A subsequent phase-equivalent modification of this N N interaction resulted in construction of the JISP16 version [1] fitted to nuclei with A ≤ 16.…”

mentioning

confidence: 99%