An insight into de Vries behaviour of smectic liquid crystals from atomistic molecular dynamics simulations

Abstract

Fully atomistic molecular dynamics simulations have been performed on the ferroelectric liquid crystal compound 9HL, which exhibits de Vries character. Simulations were carried out at a range of temperatures, and...

Sub-layer rationale of anomalous layer-shrinkage from atomistic simulations of a fluorinated mesogen

“…0.56 reported experimentally from X-ray scattering investigation of a chiral analogue of 3M 8422, 18,86 but such discrepancies have been addressed in previous work. 34,51 In this work two sets of P 2 values were calculated, determined from two different axes within the molecule. The principle molecular axis was defined as that calculated from the minimum moment of inertia (MOI) of the whole molecule, while the second axis was determined from the MOI of only those atoms in the aromatic core.…”

“…MD simulations were performed at 10 K intervals between 280 K and 330 K, employing an identical scale-up method to that described in the previous computational study of 9HL. 51 Simulations were performed until the phase structure, characterised through determination of the orientational and translational order, appeared to be fully equilibrated. This corresponded to a minimum simulation time of 500 ns and a maximum simulation time of 900 ns in the 1024-molecule configurations.…”

“…These ODFs for 3M 8422 appear to be inconsistent with a diffuse cone SmA phase, in which molecules are tilted but without azimuthal ordering, and is consistent with the results of simulations of 9HL. 51 Visualisations of the SmA phase Fig. 6 The average layer thickness determined from simulations of 3M 8422 between 280 K and 330 K, with associated error bars.…”

“…It is comparable in magnitude to the elongation exhibited by 9HL in our previous study. 51 Major conformational changes in 3M 8422 across the simulated temperature range were also investigated by analysis of the dihedral angle distributions. All dihedrals other than those involving hydrogen atoms or directly substituted to an aromatic ring were analysed and these distributions are shown in Fig.…”

“…As the simulation of large systems has become more common studies have attempted to model such behaviour, and have successfully replicated experimental observables in a variety of systems. [47][48][49][50][51] The development of modern computational methods and tools has drastically improved the scope of MD simulations when applied to the area of liquid crystals. The effort to reproduce experimental observables with increased accuracy and investigate complex behaviours has necessitated the need for flexible force fields that can maintain a sufficient level of precision.…”