Quantum Monte Carlo calculations of nuclei withA<~7

Abstract

We report quantum Monte Carlo calculations of ground and low-lying excited states for nuclei with $A<~7$ using a realistic Hamiltonian containing the Argonne $v_{18}$ two-nucleon and Urbana IX three-nucleon potentials. A detailed description of the Green's-function Monte Carlo algorithm for systems with state-dependent potentials is given and a number of tests of its convergence and accuracy are performed. We find that the Hamiltonian being used results in ground states of both ${}^6$Li and ${}^7$Li that are stable against breakup into subclusters, but somewhat underbound compared to experiment. We also have results for ${}^6$He, ${}^7$He, and their isobaric analogs. The known excitation spectra of all these nuclei are reproduced reasonably well and we predict a number of excited states in ${}^6$He and ${}^7$He. We also present spin-polarized one-body and several different two-body density distributions. These are the first microscopic calculations that directly produce nuclear shell structure from realistic interactions that fit $\mathrm{NN}$ scattering data.