Structure and Translational Diffusion in Liquid Crystalline Phases of a Gay-Berne Mesogen: A Molecular Dynamics Study

Abstract

Structures and self-diffusion coefficients of Gay-Berne (GB) mesogens with parameterizations GB(3.0, 5.0, 2.0, 1.0) and GB(4.4, 20.0, 1.0, 1.0) were extracted from NVT Molecular Dynamics simulations. These parameterizations are commonly used in the study of mesogenic systems. Structural features of accessible phases were characterized through translational [$g_{\parallel}(r_{\parallel})$] and positional [$g_{\perp}(r_{\perp})$] radial distribution functions. Translational self-diffusion coefficients parallel ($D_{\parallel}$) and perpendicular ($D_{\perp}$) to the global director were determined. Upon cooling a mesogenic system with parameterization GB(3.0, 5.0, 2.0, 1.0), a solid-like phase forms (as deduced from diffusivity) without attaining a smectic phase. Instead, the GB(4.4, 20.0, 1.0, 1.0) parameterization yields a range of liquid crystalline phases that follows the sequence isotropic $\to$ nematic $\to$ smectic A $\to$ smectic B, for which the smectic B phase exhibits small, but measurable diffusivity. Collectively, results point to the GB(4.4, 20.0, 1.0, 1.0) parameterization as being a better candidate in capturing the typical gamut of liquid crystalline phases.