Abstract
We present a nucleus-dependent valence-space approach for calculating ground and excited states of nuclei, which generalizes the shell-model in-medium similarity renormalization group to an ensemble reference with fractionally filled orbitals. Because the ensemble is used only as a reference, and not to represent physical states, no symmetry restoration is required. This allows us to capture three-nucleon () forces among valence nucleons with a valence-space Hamiltonian specifically targeted to each nucleus of interest. Predicted ground-state energies from carbon through nickel agree with results of other large-space ab initio methods, generally to the 1% level. In addition, we show that this new approach is required in order to obtain convergence for nuclei in the upper and shells. Finally, we address the inversion problem in and . This approach extends the reach of ab initio nuclear structure calculations to essentially all light- and medium-mass nuclei.
- Received 11 July 2016
DOI:https://doi.org/10.1103/PhysRevLett.118.032502
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