Efficacy of the SU(3) scheme for ab initio large-scale calculations beyond the lightest nuclei

Abstract

We report on the computational characteristics of ab initio nuclear structure calculations in a symmetry-adapted no-core shell model (SA-NCSM) framework. We examine the computational complexity of the current implementation of the SA-NCSM approach, dubbed LSU3shell, by analyzing ab initio results for 6 Li and 12 C in large harmonic oscillator model spaces and SU(3)-selected subspaces. We demonstrate LSU3shell's strong-scaling properties achieved with highly-parallel methods for computing the many-body matrix elements. Results compare favorably with complete model space calculations and significant memory savings are achieved in physically important applications. In particular, a well-chosen symmetry-adapted basis affords memory savings in calculations of states with a fixed total angular momentum in large model spaces while exactly preserving translational invariance.

Importance Truncation in the SU(3) Symmetry-adapted No-core Shell Model

“…We augmented the SA-NCSM framework as implemented by the stateof-art code LSU3shell [12] by the IT algorithm. As the proof-of-concept study, we investigated the lowest lying states of 6 Li using realistic JISP16 nucleon-nucleon interaction [5] and HO energy Ω = 20 MeV.…”

Importance Basis Truncation in the Symmetry-adapted No-core Shell Model

“…We augmented the SA-NCSM framework as implemented by the stateof-art code LSU3shell [12] by the IT algorithm. Here, we investigate performance of IT procedure for low-lying 0 + 1 , 2 + 1 , 4 + 1 states of 12 C using realistic chiral NNLO opt nucleon-nucleon interaction [5] in the configuration space up to N max = 6.…”

Accelerating many-nucleon basis generation for high performance computing enabled ab initio nuclear structure studies

“…Over the past two decades, first-principles numerical studies of nuclei and nuclear reactions have been routinely facilitating leadership class of high performance computing systems. To extend the reach of ab initio methods toward heavier nuclei, we have developed a novel method dubbed symmetry-adapted no-core shell model (SA-NCSM) (Dytrych et al, 2013) and implemented it as a suite of highly scalable computer codes 1 (Dytrych et al, 2016). Our approach is to solve the Schrödinger equation for a many-nucleon quantum system interacting via realistic interactions that are tied to the underlying quark/gluon considerations.…”