EPSRC Grant:  GR/M21676/01  01/10/1999-30/09/2002
Computer simulation of liquid crystal phases using atomistic potentials.

Final Abstract
Molecular dynamics simulations of liquid crystal systems will be carried out using atomistic potentials to model detailed molecular structure. Two basic models will be used. In model 1, molecules will be represented by Lennard-Jones 12:6 atoms. In model 2, molecules will be composed of Gay-Berne particles and Lennard-Jones sites. Both models will use data from large scale density functional theory calculations to determine intramolecular potentials. Model 1 will be used to determine accurate data for structural and dynamical properties for molecules in nematic liquid crystals, and provide the first accurate predictions for rotational viscosities of a realistic representation of a nematic phase. Model 2 will be used to carry out simulations of macromolecular liquid crystals and study molecular organisation in these systems. Simulations of a chiral dopant molecule in a Gay-Berne solvent will also be carried out. These calculations will be used to provide reliable predictions for  helical twisting power of chiral dopants. Together with other techiniques, these calculations will be used to provide insights into the phenomenon of temperature-induced twist inversion.


Objectives
1) Use atomistic models to simulate nematic liquid crystals.
a) Study  realistic model mesogens in the isotropic and nematic phases and produce reliable predictions for material properties and orientational order parameters;
b) Provide predictions for the internal structure of molecules in a nematic phase and study the coupling between internal structure and orientational ordering of molecules.
2) Carry out the first calculation of rotational viscosities in the nematic phase using atomistic models.
3) Simulate macromolecular liquid crystals (Based on a combination of Gay-Berne and atomistic potentials), and study molecular organisation in these materials.
4) Provide reliable predictions for the helical twisting power of liquid crystal chiral dopants.
Mark Wilson

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