Nonperturbative shell-model interactions from the in-medium similarity   renormalization group
  We present the first ab initio construction of valence-space Hamiltonians for medium-mass nuclei based on chiral two- and three-nucleon interactions using the in-medium similarity renormalization group. When applied to the oxygen isotopes, we find experimental ground-state energies are well reproduced, including the flat trend beyond the drip line at 24O. Similarly, natural-parity spectra in 21,22,23,24O are in agreement with experiment, and we present predictions for excited states in 25,26O. The results exhibit a weak dependence on the harmonic-oscillator basis parameter and reproduce spectroscopy within the standard sd valence space. 
S. K. Bogner, H. Hergert, J. D. Holt, A. Schwenk, S. Binder, A. Calci,   J. Langhammer, R. Roth
nucl-th nucl-ex