Validating an optimized GAFF force field for liquid crystals: <i>T</i>_NI predictions for bent-core mesogens and the first atomistic predictions of a dark conglomerate phase

Abstract

The GAFF-LCFF force field [N. J. Boyd et al., Phys. Chem. Chem. Phys., 2015, 17, 24851] is tested and further improved for use in the simulation of bent-core liquid crystal mesogens. Atomistic simulations are carried out on four systems of bent-core nematogens based on a central bis-(phenyl)oxadiazole (ODBP) motif, providing excellent agreement with experimental, T_NI, transition temperatures. Simulations of one bent-core system (C5-Ph-ODBP-Ph-OC12) indicate the presence of a dark conglomerate (DC) phase, with the prediction of a highly unusual nematic to DC phase transition.