  We study an off-lattice protein toy model with two species of monomers
interacting through modified Lennard-Jones interactions. Low energy
configurations are optimized using the pruned-enriched-Rosenbluth method
(PERM), hitherto employed to native state searches only for off lattice models.
For 2 dimensions we found states with lower energy than previously proposed
putative ground states, for all chain lengths $\ge 13$. This indicates that
PERM has the potential to produce native states also for more realistic protein
models. For $d=3$, where no published ground states exist, we present some
putative lowest energy states for future comparison with other methods.
