Crystals of Janus colloids at various interaction ranges

We investigate the effect of interaction range on the phase behaviour of Janus particles with a Kern-Frenkel potential. Specifically, we study interaction ranges Delta = 0.1 sigma, 0.3 sigma, 0.4 sigma, 0.5 sigma with sigma the particle diameter, and use variable box shape simulations to predict crystal structures. We found that changing the interaction range beyond 0.2 sigma drastically increases the variety of possible crystal structures. In addition to close-packed structures, we find body-centered tetragonal and AA-stacked hexagonal crystals, as well as several lamellar crystals. For long interaction ranges and low temperatures, we also observe an extremely large number of metastable structures which compete with the thermodynamically stable ones. These competing structures hinder the detection of the lowest-energy crystal structures, and are also likely to interfere with the spontaneous formation of the ground-state structure. Finally, we determine the gas-liquid coexistence curves for several interaction ranges, and observe that these are metastable with respect to crystallization. Published by AIP Publishing.