Spin-orbit decomposition of ab initio nuclear wavefunctions

Although the modern shell-model picture of atomic nuclei is built from single-particle orbitgs with good total angular momentum $j$ leading to $j$-$j$ coupling schemes, phenomenological models decades ago suggested for $0p$ nuclei a simpler picture can be realized by coupling of total orbital angular momentum $L$ and total spin $S$. I revisit this idea with large-basis, no-core shell model (NCSM) calculations using modern \textit{ab initio} two-body interactions and dissect the resulting NCSM wavefunctions into their $L$- and $S$-components. Remarkably, despite a gap of nearly fifty years and six orders of magnitude in the basis dimension, there is broad agreement between NCSM and phenomenological wavefunctions computed with the Cohen-Kurath force.