Ab initio no-core shell model and microscopic reactions: Recent achievements

Quaglioni, Sofia; Navrátil, Petr

doi:10.1007/s00601-008-0322-7

Cited by 9 publications

(8 citation statements)

References 15 publications

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“…While great progress has been made in extending the reach of ab initio wave function methods beyond the lightest nuclei [1][2][3][4], the EDF approach remains the most computationally feasible method for a comprehensive description of medium and heavy nuclei [5]. However, the ab initio methods are vital tools for reaching the goal of robust functionals informed by microscopic internucleon interactions.…”

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confidence: 99%

Testing the density matrix expansion againstab initiocalculations of trapped neutron drops

et al. 2011

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Microscopic input to a universal nuclear energy density functional can be provided through the density matrix expansion (DME), which has recently been revived and improved. Several DME implementation strategies are tested for neutron drop systems in harmonic traps by comparing to Hartree-Fock (HF) and ab initio no-core full configuration (NCFC) calculations with a model interaction (Minnesota potential). The new DME with exact treatment of Hartree contributions is found to best reproduce HF results and supplementing the functional with fit Skyrme-like contact terms shows systematic improvement toward the full NCFC results.

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confidence: 99%

Testing the density matrix expansion againstab initiocalculations of trapped neutron drops

et al. 2011

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“…High-quality ab-initio many-body methods have been revived or developed in the last ten years to go beyond the p-shell nuclei that were and are still addressed with success on the basis of, e.g., Faddeev-Yakubowski [1][2][3], Green function Monte-Carlo [4][5][6] or the no-core shell model [7][8][9][10] methods. A decisive step was the re-introduction of coupled cluster (CC) techniques to nuclear theory [11][12][13][14][15][16][17][18][19] after a long period of intense development in quantum chemistry [20].…”

Section: Introductionmentioning

confidence: 99%

Symmetry broken and restored coupled-cluster theory: I. Rotational symmetry and angular momentum

Duguet

2014

J. Phys. G: Nucl. Part. Phys.

166

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We extend coupled-cluster theory performed on top of a Slater determinant breaking rotational symmetry to allow for the exact restoration of the angular momentum at any truncation order. The main objective relates to the description of near-degenerate finite quantum systems with an openshell character. As such, the newly developed many-body formalism offers a wealth of potential applications and further extensions dedicated to the ab initio description of, e.g., doubly open-shell atomic nuclei and molecule dissociation. The formalism, which encompasses both single-reference coupled cluster theory and projected Hartree-Fock theory as particular cases, permits the computation of usual sets of connected diagrams while consistently incorporating static correlations through the highly non-perturbative restoration of rotational symmetry. Interestingly, the yrast spectroscopy of the system, i.e. the lowest energy associated with each angular momentum, is accessed within a single calculation. A key difficulty presently overcome relates to the necessity to handle generalized energy and norm kernels for which naturally terminating coupled-cluster expansions could be eventually obtained. The present work focuses on SU (2) but can be extended to any (locally) compact Lie group and to discrete groups, such as most point groups. In particular, the formalism will be soon generalized to U (1) symmetry associated with particle number conservation. This is relevant to Bogoliubov coupled cluster theory that was recently applied to singly open-shell nuclei. 0 can be extracted as

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“…A longstanding challenge of nuclear theory is to calculate properties of nuclei starting from the vacuum two-and three-nucleon interactions. While impressive progress has been made in extending the limits of abinitio methods beyond the lightest nuclei [1][2][3], the nuclear energy density functional (EDF) approach remains the most computationally feasible method for a comprehensive description of medium and heavy nuclei [4]. Modern parameterizations of empirical Skyrme and Gogny EDFs provide a good description of bulk properties and, to a lesser extent, of certain spectroscopic features of known nuclei.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, while a Hartree-Fock calculation using the un-evolved chiral EFT NN interaction would provide a very poor description of nuclei, the application of the DME to such contributions captures some of the same density dependencies that would arise from the finiterange tail of any in-medium vertex (e.g., a G matrix or a perturbative approximation thereof) that sums ladder diagrams in a more sophisticated many-body treatment. Once a satisfactory generalization of the DME is developed to handle spatial and temporal non-locality on the same footing, non-localities arising from in-medium propagation can be mapped into the density-dependent Skyrme couplings as well 2 . The rest of the paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Microscopically-constrained Fock energy density functionals from chiral effective field theory. I. Two-nucleon interactions

2011

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The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finiterange physics associated with vacuum two-and three-nucleon interactions into the form of a Skymelike energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DME proposed recently in arXiv:0910.4979 by Gebremariam et al. to the non-local Fock energy obtained from chiral effective field theory (EFT) two-nucleon (NN) interactions at next-to-next-to-leading-order (N 2 LO). The structure of the chiral interactions is such that each coupling in the DME Fock functional can be decomposed into a cutoff-dependent coupling constant arising from zero-range contact interactions and a cutoff-independent coupling function of the density arising from the universal long-range pion exchanges. This motivates a new microscopically-guided Skyrme phenomenology where the density-dependent couplings associated with the underlying pion-exchange interactions are added to standard empirical Skyrme functionals, and the density-independent Skyrme parameters subsequently refit to data. A Mathematica notebook containing the novel density-dependent couplings is provided.

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Ab initio no-core shell model and microscopic reactions: Recent achievements

Abstract: We report on recent microscopic calculations of reaction properties based upon the nuclear structure of the ab initio no-core shell model (NCSM).

Cited by 9 publications

References 15 publications

Testing the density matrix expansion againstab initiocalculations of trapped neutron drops

Testing the density matrix expansion againstab initiocalculations of trapped neutron drops

Symmetry broken and restored coupled-cluster theory: I. Rotational symmetry and angular momentum

Microscopically-constrained Fock energy density functionals from chiral effective field theory. I. Two-nucleon interactions

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