Improved sd shell effective interactions from Daejeon16

TL;DR

This paper develops new microscopic effective interactions for the sd shell using the Daejeon16 nucleon-nucleon potential and no-core shell-model calculations, improving agreement with experimental nuclear spectra.

Contribution

The paper introduces a novel method to derive sd-shell effective interactions from Daejeon16 using NCSM wave functions, enhancing accuracy over previous models.

Findings

Improved convergence of excitation energies in 18F.

Enhanced agreement with experimental spectra of sd-shell nuclei.

Monopole modifications further improve interaction accuracy.

Abstract

We present new microscopic effective shell-model interactions in the valence sd shell, obtained from the modern Daejeon16 nucleon-nucleon potential using no-core shell-model (NCSM) wave functions of 18F at Nmax=6 (total oscillator quanta of excitation) model space and the Okubo-Lee-Suzuki transformation. First, we explore the convergence properties of our calculations and show that the excitation energies of states in 18F, characterized by the largest valence-like configurations, are reasonably converged and the lowest states are in sensible agreement with experiment. Then, we investigate the monopole properties of that interaction in comparison with the phenomenological universal sd-shell interaction, USDB, and with the previously derived interaction at Nmax=4. Theoretical binding energies and low-energy spectra of the O isotopes, as well as low-energy spectra of a selection of $sd$-shell nuclei, are presented. We conclude that the use of larger-space NCSM wave functions leads to a noticeable improvement in the quality of the derived effective interaction. We propose monopole modifications of the Daejeon16 centroids which further improve the agreement with experiment throughout the sd shell, as demonstrated by a compilation of spectra contained in Supplemental Material.