FCC-to-BCC phase transitions in convex and concave hard particle systems

Particle shape plays an important role in the phase behavior of colloidal self-assembly. Recent progress in particle synthesis has made particles of polyhedral shapes and dimpled spherical shapes available. Here using computer simulations of hard particle models, we study face-centered cubic to body-centered cubic (FCC-to-BCC) phase transitions in a convex 432 polyhedral shape family and a concave dimpled sphere family. Particles in both families have four-, three-, and two-fold rotational symmetries. Via free energy calculations we find the FCC-to-BCC transitions in both families are first order. As a previous work reports the FCC-to-BCC phase transition is first order in a convex 332 family of hard polyhedra, our work provides additional insight into the FCC-to-BCC transition and how the convexity or concavity of particle shape affects phase transition pathways.