Shell model description of the isotonic chain with a new effective interaction
Phys. Rev. C 113, 024318 – Published 12 February, 2026
DOI: https://doi.org/10.1103/shhh-41cg
Abstract
In this work, we present a systematic study of low-lying states and electromagnetic properties of the semimagic isotonic chain with proton number = 51–77, using the full configuration interaction shell model with a newly developed high-quality effective interaction. The calculations are performed in a large model space that includes all proton orbitals between and 82: , and . The effective interaction is derived through the principal component analysis approach, starting from 160 two-body matrix elements and five single-particle energies and considering up to 30 degrees of freedom. Those are optimized by fitting to 204 available experimental energy levels. The resulting root-mean-square deviation is as low as 102 keV. The new interaction successfully reproduces the binding energies, low-lying spectra, electric quadrupole transition probabilities , and magnetic dipole moments across both even-even and odd-mass isotones. The nuclear structure of low-lying states is analyzed in detail. Additionally, predictions are made for several more proton-rich nuclei beyond current experimental reach, including , and .