  We calculate properties of neutron drops in external potentials using both
quantum Monte Carlo and no-core full configuration techniques. The properties
of the external wells are varied to examine different density profiles. We
compare neutron drop results given by a selection of nuclear Hamiltonians,
including realistic two-body interactions as well as several three-body forces.
We compute a range of properties for the neutron drops: ground-state energies,
spin-orbit splittings, excitation energies, radial densities and rms radii. We
compare the equations of state for neutron matter for several of these
Hamiltonians. Our results can be used as benchmarks to test other many-body
techniques, and to constrain properties of energy-density functionals.
