Molecular dynamics calculation of elastic constants in Gay-Berne nematic liquid crystals

Abstract

<F4.417e+05> In this paper we present a molecular dynamics calculation of the Frank elastic constants of a nematic liquid crystal. We study two well-known variants of the Gay-Berne potential, and determine the elastic constants by measuring orientational fluctuations as a function of wavevector, using reasonably large system sizes in the range 1000--8000 molecules. For some of the simulations, a set of Lagrangian constraints was applied in order to keep the director fixed along one of the box axes, facilitating the measurement of fluctuations in components of the reciprocal-space order tensor <F5.754e+05><F5.273e+05><F5.754e+05><F5.273e+05> Q(k)<F4.417e+05> in the director frame. <F5.754e+05>1 Introduction<F4.417e+05> In a nematic liquid crystal, the distribution of molecular positions is translationally invariant but the orientational distribution shows preferential alignment along the director. Deviations from uniform alignment occur principally through the existence of defects (..