Collective excited states of a model ¹⁶O nucleus

As a first step toward developing a coordinate-space based, microscopic theory of nuclear giant resonances, we apply Feynman's theory of collective excitation to the study of excited states of a model ¹⁶O nucleus. This is a system of 16 nucleons interacting via a purely central Malfliet-Tjon potential. For this Fermi system, our modified, fixed-node diffusion Monte Carlo algorithm yields excellent results for the ground-state energy and one- and two-body densities. By solving the Feynman eigenvalue equation using these densities as inputs, we can further determine the energy and the transition densities of the collective monopole, dipole and quadrupole excitations.