Enantiopure molecules form apparently racemic monolayers of chiral cyclic pentamers

-proline. Straightforward geometry optimization proved difficult, as the size of the cluster and the number of possible intermolecular interactions produced an interaction potential with multiple local minima. Instead, the Amber force field was used to exhaustively search all of phase space for chemically reasonable pentamer structures, producing a limited number of candidate structures that were then optimized as gas-phase clusters using density functional theory (DFT). The binding energies of the two lowest-energy pentamers on the Au(111) surface were then calculated by plane-wave DFT using the VASP software, and STM images predicted. These calculations indicate that the right- and left-handed pentamers are instead two different polymorphs.