GPU-Accelerated Molecular Dynamics Simulation to Study Liquid Crystal Phase Transition Using Coarse-Grained Gay-Berne Anisotropic Potential

Abstract

Gay-Berne (GB) potential is regarded as an accurate model in the simulation of anisotropic particles, especially for liquid crystal (LC) mesogens. However, its computational complexity leads to an extremely time-consuming process for large systems. Here, we developed a GPU-accelerated molecular dynamics (MD) simulation with coarse-grained GB potential implemented in GALAMOST package to investigate the LC phase transitions for mesogens in small molecules, main-chain or side-chain polymers. For identical mesogens in three different molecules, on cooling from fully isotropic melts, the small molecules form a single-domain smectic-B phase, while the main-chain LC polymers prefer a single-domain nematic phase as a result of connective restraints in neighboring mesogens. The phase transition of side-chain LC polymers undergoes a two-step process: nucleation of nematic islands and formation of multi-domain nematic texture. The particular behavior originates in the fact that the rotational orientation of the mesogenes is hindered by the polymer backbones. Both the global distribution and the local orientation of mesogens are critical for the phase transition of anisotropic particles. Furthermore, compared with the MD simulation in LAMMPS, our GPU-accelerated code is about 4 times faster than the GPU version of LAMMPS and at least 200 times faster than the CPU version of LAMMPS. This study clearly shows that GPU-accelerated MD simulation with GB potential in GALAMOST can efficiently handle systems with anisotropic particles and interactions, and accurately explore phase differences originated from molecular structures.

Origin and structure of liquid crystalline Blue Phase III

“…In our MD simulation, the force and torque equations for all the N molecules have been solved through the Leap-frog Verlet integrator method to follow the real trajectory of the system in phase space. For this reason, MD simulation is much expensive computationally 30,31 . To understand the phase structure of polar chiral liquid crystal molecules, we have used an NVT algorithm in this work which is developed by us and used in our earlier works 19,32 .…”

Assembled Structures of Perfluorosulfonic Acid Ionomers Investigated by Anisotropic Modeling and Simulations

“…The crystallites of PTFE backbone can be identified from the orientation of anisotropic backbone particles A/A′. The radial distribution function of backbone g ( r ) and the second-rank orientation correlation function g 2 ( r ) of PTFE backbone are presented in Figure a and b. The value of g 2 ( r ) equals to 1 means that orientation within the intralayers is aligned, while the value 0 means the isotropic phase.…”

“…We construct an anisotropic coarse-grained model equipped with Gay-Berne (GB) , and Lennard-Jones (LJ) potentials to describe the Nafion and water molecules, as shown in Figure S1 of Supporting Information S1. Each monomer of Nafion is represented by four CG particles.…”

New Patchy Particle Model with Anisotropic Patches for Molecular Dynamics Simulations: Application to a Coarse-Grained Model of Cellulose Nanocrystal

“…where U h and U a are respectively a harmonic bond potential and a cosine harmonic angle, similar to the potentials used by Chen et al in Ref. 83, and U d is a dihedral potential that we designed. The harmonic bond potential writes…”