Marlics: A finite difference liquid crystal simulation package

Abstract

In this paper we present Marlics (Maringá Liquid Crystal Simulator), a software written in C++ to obtain either the system dynamics, by using the Runge-Kutta method, or the minimum energy states with the Fast Inertial Relaxation Engine (FIRE) for both achiral and chiral nematic liquid crystals. The system solved by Marlics consists in the dynamical evolution for the Q-tensor in the Landau-de Gennes formalism for different geometries, including confined slab cells and spherical, liquid crystal droplets. Furthermore, the code accepts custom geometries, so the user may provide a particular geometry of interest to run simulations. The program takes as input a descriptive file giving the simulations parameters and initial conditions, generating a series of different snapshots distributed in time according to the users' needs. Several initial conditions are provided to help the user starting simulations direct to different goals. The code is organized in class modules, which can be modified by the user base to attend their further needs. Program summaryProgram Title: MarLicSCPC Library link to program files:https://doi.org/10.17632/xb728xftgv.1Code Ocean capsule:https://codeocean.com/capsule/5639788Licensing provisions: GNU General Public License v3.0Programming language: C++Supplementary material: In the S.I the user will find an input file example and the complete list of setup parameters.External routines: The code needs the GSL (Gnu scientific library), an implementation of the CBLas library and an implementation of the OpenMp library (optional).Nature of problem: Marlics was developed to simulate liquid crystal devices via solution of the Landau-de Gennes Equation.Solution method: The system of equations is solved using finite differences in both time and space. The time integration is performed using an explicit integrator with or without variable time-step. We also provide a relaxation engine (FIRE), which is specialized in finding equilibrium states of the same system of dynamical equations.Additional comments including restrictions and unusual features: The code is parallelized using OpenMp, consequently it can only be run in parallel with shared memory processors.The source code comes with the input files and scripts used to generate the results and figures showed in this work.