Investigation of excitation energies and Hund's rule in open shell quantum dots by diffusion Monte CarloL. Colletti, F. Pederiva, E. Lipparini and C. J. UmrigarEur. Phys. J. B, 27 3 (2002) 385-392DOI: https://doi.org/10.1140/epjb/e2002-00169-x