Abstract
A simple dissipative particle dynamics (DPD) model is introduced, which can be used to represent a broad range of calamitic mesogens. The model allows for antiparallel association that occurs naturally in a number of mesogens with terminal dipoles, including the 4-n-alkyl-4'-cyanobiphenyl (nCB) series. Favourable antiparallel interactions lead to the formation of SmAd phases in which the layer spacing is intermediate between monolayer and bilayer. The model is easily tuned to vary the strength of antiparallel association and the SmA layer spacing, and to give either isotropic-smectic or isotropic-nematic-smectic phase sequences. The model allows for a range of other smectics: including SmA1 phases exhibiting microphase separation within layers, and smectics A structures with more complicated repeat units. For large system sizes (≥50 000 molecules) in the nematic phase, we are able to demonstrate the formation of three distinct types of cybotactic domains depending on the local interactions. Cybotactic domains are found to grow in the nematic-smectic pretransitional region as the system moves closer to TSN.
Highlights
Thermotropic liquid crystals represent a fascinating area of soft matter science
We present a coarse-grained dissipative particle dynamics (DPD) model for liquid crystal molecules, in which the effects of specific molecular interactions can be incorporated
We present a simple DPD model, which can be used to represent calamitic mesogens
Summary
High interest arises from the wide range of different liquid crystal mesophases that have been produced by Chemists; and from the large number of commercial applications. The former includes new forms of nematic phase,[1] and a preponderance of smectic phases of varying degrees of translation and rotational order.[2] Applications cover the areas of thermochromic materials,[3] lasers,[4] high-tech lubricants,[5] liquid crystal displays,[6] and a range of optoelectronic applications such as optical filters and switches, beam-steering devices and spatial light modulators.[7]. As computational power increased the development of anisotropic-attractive-coarsegrained models, such as the Gay-Berne potential,[13,14,15] led to increased
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