Atomistic Mechanism of Anisotropic Heat Conduction in the Liquid Crystal 4-Heptyl-4'-Cyanobiphenyl: All-atom Molecular Dynamics.

All-atom molecular dynamics simulations were performed on 4-heptyl-4’-cyanobiphenyl (7CB) to study the mechanism of heat conduction in this nematic liquid crystal atomistically. To describe 7CB properly, the AMBER-type force field was optimized for the dihedral parameter of biphenyl and the Lennard-Jones parameters. The molecular dynamics calculation using the optimized force field well reproduced the experimental values of the isotropic-nematic phase transition temperature, density, and anisotropy of the thermal conductivity. The predicted thermal conductivity of bulk 7CB is considered to be an upper limit that was calculated without the influence of the domain interface and impurities. Furthermore, the contributions of convection, intramolecular interaction, and intermolecular interaction to the thermal conductivity were determined by performing thermal conductivity decomposition analysis. According to the analysis, the contributions of convection and bond stretching and bond bending interactions were h...