Understanding the Structure of Medium-Mass Nuclei from First Principles

We present applications of the In-Medium Similarity Renormalization Group (IMSRG) framework in ab initio nuclear structure theory. We present two complementary strategies for the computation of nuclear ground- and excited- state properties, namely direct evaluations and the derivation of valence-space interactions for the nuclear configuration interaction (Shell model) approach. We highlight recent results for ground- and excited state observables of sd- and pf-shell nuclei, and look ahead at the next steps towards a predictive ab initio theory of medium-mass nuclei.