Quantum Monte Carlo calculations of excited states in A = 6--8 nuclei

Abstract

A variational Monte Carlo method is used to generate sets of orthogonal trial functions, Psi_T(J^pi,T), for given quantum numbers in various light p-shell nuclei. These Psi_T are then used as input to Green's function Monte Carlo calculations of first, second, and higher excited (J^pi,T) states. Realistic two- and three-nucleon interactions are used. We find that if the physical excited state is reasonably narrow, the GFMC energy converges to a stable result. With the combined Argonne v_18 two-nucleon and Illinois-2 three-nucleon interactions, the results for many second and higher states in A = 6--8 nuclei are close to the experimental values.Comment: Revised version with minor changes as accepted by Phys. Rev. C. 11 page