Ab initio results for intermediate-mass, open-shell nuclei

A theoretical understanding of nuclei in the intermediate-mass region is vital to astrophysical models, especially for nucleosynthesis. Here, we employ the \emph{ab initio} symmetry-adapted no-core shell model (SA-NCSM) in an effort to push first-principle calculations across the \emph{sd}-shell region. The \emph{ab initio} SA-NCSM's advantages come from its ability to control the growth of model spaces by including only physically relevant subspaces, which allows us to explore ultra-large model spaces beyond the reach of other methods. We report on calculations for $^{19}$Ne and $^{20}$Ne up through 13 harmonic oscillator shells using realistic interactions and discuss the underlying structure as well as implications for various astrophysical reactions.