Medium-Mass Nuclei with Normal-Ordered Chiral NN+3N Interactions

We study the use of truncated normal-ordered three-nucleon interactions in nuclear structure calculations starting from chiral two-plus three-nucleon Hamiltonians evolved consistently with the similarity renormalization group. We present three key developments: (i) a rigorous benchmark of the normal-ordering approximation in the importance-truncated no-core shell model for He-4, O-16, and Ca-40; (ii) a direct comparison of the importance-truncated no-core shell model results with coupled-cluster calculations at the singles and doubles level for 16O; and (iii) first applications of similarity renormalization group-evolved chiral NN + 3N Hamiltonians in coupled-cluster calculations for medium-mass nuclei O-16,O-24 and Ca-40,Ca-48. We show that the normal-ordered two-body approximation works very well beyond the lightest isotopes and opens a path for studies of medium-mass and heavy nuclei with chiral two-plus three-nucleon interactions. At the same time we highlight the predictive power of chiral Hamiltonians.