Large-scale exact diagonalizations reveal low-momentum scales of nuclei
Journal article, 2018

Ab initio methods aim to solve the nuclear many-body problem with controlled approximations. Virtually exact numerical solutions for realistic interactions can only be obtained for certain special cases such as few-nucleon systems. Here we extend the reach of exact diagonalization methods to handle model spaces with dimension exceeding 10(10) on a single compute node. This allows us to perform no-core shell model (NCSM) calculations for Li-6 in model spaces up to N-max = 22 and to reveal the He-4+d halo structure of this nucleus. Still, the use of a finite harmonic-oscillator basis implies truncations in both infrared (IR) and ultraviolet (UV) length scales. These truncations impose finite-size corrections on observables computed in this basis. We perform IR extrapolations of energies and radii computed in the NCSM and with the coupled-cluster method at several fixed UV cutoffs. It is shown that this strategy enables information gain also from data that is not fully UV converged. IR extrapolations improve the accuracy of relevant bound-state observables for a range of UV cutoffs, thus making them profitable tools. We relate the momentum scale that governs the exponential IR convergence to the threshold energy for the first open decay channel. Using large-scale NCSM calculations we numerically verify this small-momentum scale of finite nuclei.

Author

Christian Forssen

Chalmers, Physics, Subatomic and Plasma Physics

Boris Karlsson

Chalmers, Physics, Subatomic and Plasma Physics

Håkan T Johansson

Chalmers, Physics, Subatomic and Plasma Physics

DANIEL SÄÄF

Chalmers, Physics, Subatomic and Plasma Physics

A. Bansal

Oak Ridge National Laboratory

University of Tennessee

G. Hagen

Oak Ridge National Laboratory

University of Tennessee

T. Papenbrock

University of Tennessee

Oak Ridge National Laboratory

PHYSICAL REVIEW C

2469-9985 (ISSN) 2469-9993 (eISSN)

Vol. 97 3 034328

Subject Categories

Computational Mathematics

Other Physics Topics

Control Engineering

DOI

10.1103/PhysRevC.97.034328

More information

Latest update

4/18/2018