(55b) Phase Transitions in Systems with Interconverting Species

The separation of substances into different phases is ubiquitous in nature and important scientifically and technologically. This phenomenon may become drastically different if the species involved interconvert. In the presence of an external force large enough to overcome energetic differences between the interconvertible species (forced interconversion), the two alternative species will be present in equal amounts, and steady-state, restricted phase separation into mesoscales is observed. We investigate the formation of such structures through simulations of physically distinct microscopic models of binary mixtures that exhibit both equilibrium (natural) interconversion and a nonequilibrium source of forced interconversion. A chiral tetramer model whose enantiomers can interconvert exhibits rich fluid-phase behavior that may have implications for pre-biotic chiral symmetry breaking. The phase transition mechanism in this system does not involve nucleation. The model’s critical point belongs to the 3D Ising universality class.