Stability of chiral crystal phase and breakdown of cholesteric phase in mixtures of active-passive chiral rods (2311.03994v1)

Abstract: In this study, we aim to explore the effect of chirality on the phase behavior of active helical particles driven by two-temperature scalar activity. We first calculate the equation of state of soft helical particles of various intrinsic chiralities using molecular dynamics (MD) simulation. In equilibrium, the emergence of various liquid crystal (LC) phases such as nematic (N), cholesteric ($N_{c}^{*}$), smectic (Sm), as well as crystal (K), crucially depends on the presence of the walls, which induce homeotropic alignment. Next, we introduce activity through the two-temperature model: keep increasing the temperature of half of the helical particles (labeled as 'hot' particles) while maintaining the temperature of the other half at a lower value (labeled as 'cold' particles). Starting from a homogeneous isotropic (I) phase, we find the emergence of 2-TIPS: two temperature-induced phase separations between the hot and cold particles. We also observe the cold particles undergo an ordering transition to various LC phases even in the absence of a wall. This observation reveals that the hot-cold interface in the active system plays the role of a wall in the equilibrium system by inducing an alignment direction for the cold particles. However, in the case of a cholesteric phase, we observe activity destabilizes the $N_{c}^{*}$ phase by inducing smectic ordering in the cold zone while isotropic structure in the hot zone. The smectic ordering in the cold zone eventually transforms to a chiral crystal phase at high enough activity.