Stability and Free Energy of Nanocrystal Chains and Superlattices*

I present simulations of hydrocarbon-capped monodisperse nanocrystal superlattices. I compute the free energy for both bcc and fcc, including several ligand lengths, as well as the entropy and Gibbs free energy. We find that bcc superlattices with oriented or random nanocrystal cores have slightly different free energy and lattice constant. Consistent with experimental findings, we observe that nanocrystals capped with relatively long ligands form bundles. We also compared our calculated lattice constants to experimental values and predictions for the OTM (Orbifold Topological Model).