Research Interests
Research Interests
Coarse graining
The diagram above shows the basic idea of “coarse-graining”. The idea is to move from a “complicated” picture of the interactions in a system, to a simpler picture, which is more amenable to the simulation of large systems (and for longer times). In the diagram this is illustrated for a liquid crystal, which is represented by each atom in the system on the far left hand side but progressively “simpler” coarse-grained descriptions in moving to the right. These simpler models are:
- a semi-atomistic model – with the rigid part of the liquid crystal molecule replaced by a single anisotropic interaction site (shown in colours), and the flexible part of the molecule replaced by a short chain of spheres (shown in white);
- a fully coarse-grained model – with each liquid crystal molecule replaced by an anisotropic interaction site;
- a lattice model, where space is now coarse-grained so that molecules (or molecular clusters) can only exist on lattice points.
The pictures below are of a main chain liquid crystal polymer in the liquid and nematic liquid crystal phases. Rigid liquid crystalline parts are shown by the coloured ellipsoids and flexible linking chains are shown by the white spheres. Careful modelling of interactions in a system like this can help researchers understand the structure and molecular order in complex phases like this.
References
- Molecular dynamics simulation of main chain liquid crystalline polymers. A.V. Lyulin, M.S. Al Barwani, M.P. Allen, M.R. Wilson, I. Neelov, N.K. Allsopp. Macromolecules, 1998, 31, 4626-4634.