Challenges for first-principles nuclear structure: $^{11}$Li and $^{29}$F

TL;DR

This paper discusses the challenges faced in first-principles nuclear structure calculations, focusing on halo nuclei $^{11}$Li and $^{29}$F, which exemplify difficulties in modeling intruder states and configuration mixing.

Contribution

It highlights the specific challenges in ab initio calculations of halo nuclei and proposes these systems as testbeds for developing improved computational approaches.

Findings

Intruder levels are slow to integrate into the lowest energy states.

Halo nuclei like $^{11}$Li and $^{29}$F exemplify key computational challenges.

These nuclei serve as prototypes for testing new methods.

Abstract

Ab initio calculations of atomic nuclei have had many successes in recent years. Nonetheless, important challenges that resist even brute-force calculation remain. As archetypal examples of these challenges, we consider $^{11}$Li and $^{29}$F, well known halo nuclides situated on islands of inversion. The deformed intruder levels, which are primarily two-particle, two-hole neutron excitations with respect to naive spherical shell model configurations, are slow, with respect to increases of the model space, to take their rightful place among, and potentially mix with, the lowest levels. We suggest these systems prototype the challenges for other important intruder states, and can serve as useful testbeds for potential approaches.