<i>Ab initio</i>multireference in-medium similarity renormalization group calculations of even calcium and nickel isotopes

Hergert, H.; Bogner, S. K.; Morris, Titus; Binder, Sven; Calci, Angelo; Langhammer, Joachim; Roth, Robert

doi:10.1103/physrevc.90.041302

Cited by 137 publications

(262 citation statements)

References 60 publications

(145 reference statements)

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“…These allow to fully exploit modern chiral interactions with two-nucleon (NN) and 3NFs evolved through SRG techniques [28]. Moreover, open shell nuclei have become arXiv:1412.0491v2 [nucl-th] 19 Jun 2015 accessible through a Gorkov extension of the SCGF formalism [22,29,30], multi-reference IM-SRG [18,23] and Bogoliubov coupled cluster (BCC) [31]. These ab initio studies have mainly focussed on ground state properties, such as total binding energies and two-nucleon separation energies.…”

Section: Introductionmentioning

confidence: 99%

Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain

2015

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Background: Three-nucleon forces (3NFs) have non trivial implications on the evolution of correlations at extreme proton-neutron asymmetries. Recent ab initio calculations show that leading order chiral interactions are crucial to obtain the correct binding energies and neutron driplines along the O, N, and F chains, Ref.[A. Cipollone, C. Barbieri, P. Navrátil, Phys. Rev. Lett 111, 062501 (2013)].Purpose: Here, we discuss the impact of 3NFs along the oxygen chain for other quantities of interest, such has the spectral distribution for attachment and removal of a nucleon, spectroscopic factors and radii. The objective is to better delineate the general effects of 3NFs on nuclear correlations. Methods:We employ self-consistent Green's function (SCGF) theory which allows a comprehensive calculation of the single particle spectral function. For the closed subshell isotopes, 14 O, 16 O, 22 O, 24 O and 28 O, we perform calculations with the Dyson-ADC(3) method which is fully non-perturbative and is the state of the art for both nuclear physic and quantum chemistry applications. The remaining open shell isotopes are studied using the newly developed Gorkov-SCGF formalism up to second order. Results:We produce complete plots for the spectral distributions. The spectroscopic factors for the dominant quasiparticle peaks are found to depend very little on the leading order (NNLO) chiral 3NFs. The latters have small impact on the calculated matter radii, which, however are consistently obtained smaller than experiment. Similarly, single particle spectra tend to be too spread with respect to the experiment. This effect might hinder, to some extent, the onset of correlations and screen the quenching of calculated spectroscopic factors. The most important effect of 3NFs is thus the fine tuning of the energies for the dominant quasiparticle states, which governs the shell evolution and the position of driplines.Conclusions: Although present chiral NNLO 3NFs interactions do reproduce the binding energies correctly in this mass region, the details of the nuclear spectral function remain at odd with the experiment showing too small radii and a too spread single particle spectrum, similar to what already pointed out for larger masses. This suggests a lack of repulsion in the present model of NN+3N interactions which is mildly apparent already for masses in the A=14-28 range.

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Section: Introductionmentioning

confidence: 99%

Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain

2015

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“…As discussed in Refs. [55,61,92] and the remainder of this section, these uncertainties can be quantified and controlled reasonably well, so that the main source of uncertainty are the input Hamiltonian and the impact of changing the resolution scale λ.…”

Section: Ground-state Calculations For Closed-and Open-shell Nucleimentioning

confidence: 99%

“…through their confrontation with experimental data [55,61,92]. We will review the salient findings of these investigations in the following, using the opportunity to repeat the MR-IMSRG(2) calculations with the Brillouin generator (101) instead of our earlier choices.…”

Section: Ground-state Calculations For Closed-and Open-shell Nucleimentioning

confidence: 99%

“…For nuclei up to the calcium and nickel region, careful analyses have shown that it is sufficient to use E 3max = 14 or 16 [57,92] for soft interactions like N N+3N (400). These E 3max require ∼ 5GB and ∼ 25 GB of memory, respectively, to store matrix elements in single precision.…”

Section: Interactions and Implementationmentioning

confidence: 99%

“…The Imaginary-Time Generator Using G pp hh to ensure that the energy denominator is always positive, we obtain the so-called imaginary-time generator [62,92,123], which is inspired by imaginary-time evolution techniques that are frequently used in Quantum Monte Carlo methods, for instance (see, e.g., [134] and references therein). Explicitly indicating the flow parameter dependence of all quantities, we define…”

Section: 32mentioning

confidence: 99%

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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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No-Core Gamow Shell Model

Michel

Płoszajczak

2021

Gamow Shell Model

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Ab initiomultireference in-medium similarity renormalization group calculations of even calcium and nickel isotopes

Cited by 137 publications

References 60 publications

Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain

Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain

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

No-Core Gamow Shell Model

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