Assist. Prof. Dr. Debabrata Deb (Thapar Inst of E&T): Gay-Berne liquid crystal in two dimensions

Date of publication: 28. 9. 2023
Monday physics colloquium
16:15 - 17:15

It is well established that the melting of two-dimensional (2D) crystals occurs through the unbinding of topological defects, first the unbinding of dislocation pairs and later dissociation into disclinations. However, when the constituent particles are aspherical in shape, topological defects due to their orientational property also appear in the system. Therefore, such orientational defects are expected to also play a role in the melting of 2D liquid crystalline (LC) systems. Here, we report the results of molecular dynamics simulations of a 2D LC system consisting of soft ellipses. The Gay-Berne (GB) potential governs the interaction between the constituent ellipses. We focused our study on the systems’ high-density states as the orientational property remains relevant only up to liquid crystalline nematic phases. We observed an interplay of positional and orientational defects during the melting of the 2D solid phase. We constructed a phase diagram for the dense GB system in the (ρ,T) plane. As an extension of this study, we also looked at the influence of an underlying substrate in the phase behavior of the 2D LC system. We have found substrate-induced freezing, melting, and structural depinning transitions occurring in the system as a function of the substrate periodicity parameter.
[1] Bharti, D. Deb, Melting of dense liquid crystalline Gay-Berne system in two dimensions, under review.
[2] Bharti, D. Deb, Novel smectic phases and orientational order switching in two-dimensional liquid crystalline system, Liq. Crys., 42 1983 (2022).
[3] Bharti, D. Deb, Substrate induced freezing, melting and structural depinning transitions in two-dimensional liquid crystalline system, Phys. Chem. Chem. Phys. 24, 5154 (2022).