Phase diagram of hard asymmetric dumbbell particles

Abstract

Using Monte Carlo simulations and free energy calculations, we study the phase behavior of hard asymmetric dumbbell particles with a constituent sphere diameter ratio of 0.5. We find a rich phase behavior with isotropic fluid, rotator, and periodic NaCl-based and both periodic and aperiodic CrB-based crystalline phases. The rotator phases found to be stable in this study are similar to those found in systems of snowman-shaped and dumbbell particles and we investigate the behavior of these phases by comparing their stability ranges, and by looking at the orientational reorganization of particles. We also find that the NaCl-based crystalline phase can expand its range of stability by undergoing a slight modification which allows it to pack better. Finally, we see that reducing the sphere separation results in the aperiodic crystalline phases becoming destabilized as compared to the phase behavior of snowman-shaped particles.