Quantum Monte Carlo calculations of A=9,10 nuclei

We report on quantum Monte Carlo calculations of the ground and low-lying excited states of A=9,10 nuclei using realistic Hamiltonians containing the Argonne v₁₈ two-nucleon potential alone or with one of several three-nucleon potentials, including Urbana IX and three of the new Illinois models. The calculations begin with correlated many-body wave functions that have an α-like core and multiple p-shell nucleons, LS-coupled to the appropriate (J^π;T) quantum numbers for the state of interest. After optimization, these variational trial functions are used as input to a Green’s function Monte Carlo calculation of the energy, using a constrained path algorithm. We find that the Hamiltonians that include Illinois three-nucleon potentials reproduce ten states in ⁹Li, ⁹Be, ¹⁰Be, and ¹⁰B with an rms deviation as little as 900 keV. In particular, we obtain the correct 3⁺ ground state for ¹⁰B, whereas the Argonne v₁₈ alone or with Urbana IX predicts a 1⁺ ground state. In addition, we calculate isovector and isotensor energy differences, electromagnetic moments, and one- and two-body density distributions.