(451i) Vapor-Liquid-Liquid Phase Transition of a Chiral Tetramer Model

Chirality is an essential phenomenon underlying biological evolution and pharmaceutical industrial syntheses. Understanding the chiral symmetry-breaking phase transitions exhibited by many chiral molecules provides basic insights for both of these important subjects. In this work, we have performed molecular dynamics simulations to investigate the vapor-liquid and chirality-induced liquid-liquid phase transitions using a flexible 3-dimensional four-site (tetramer) chiral molecular model developed by Latinwo et al. (J. Chem. Phys. 145, 154503, 2016). By constructing a temperature-density-composition phase diagram, we show that in the high temperature regime, the system behaves as an effective L/D binary mixture and exhibits a density-dependent liquid-liquid critical locus due to the insufficient L/D interconversion events within the time scale of system relaxation. The vapor-liquid coexistence region exists below the liquid-liquid critical locus where the system contains vapor-liquid-liquid phase co-existence. In coexistence with the achiral vapor phase, the liquid always maintains a single chiral phase which undergoes very infrequent interconversions between the L-rich and D-rich states. These simulation results provide basic thermodynamic insights for generally understanding many-body chiral phenomena, including their phase transition consequences.