Convergence in the no-core shell model with low-momentum two-nucleon interactions

摘要

The convergence of no-core shell model (NCSM) calculations usingrenormalization group evolved low-momentum two-nucleon interactions is studiedfor light nuclei up to Li-7. Because no additional transformation was used inapplying the NCSM framework, the energy calculations satisfy the variationalprinciple for a given Hamiltonian. Dramatic improvements in convergence arefound as the cutoffs are lowered. The renormalization group equations aretruncated at two-body interactions, so the evolution is only approximatelyunitary and converged energies for A > 2 vary with the cutoff. Thisapproximation is systematic, however, and for useful cutoff ranges the energyvariation is comparable to natural-size truncation errors inherent from theinitial chiral effective field theory potential.