Elastic continuum theory: towards understanding of the twist-bend nematic phases.

摘要: The twist-bend nematic phase, N_{TB}, may be viewed as a heliconical molecular arrangement in which the director n precesses uniformly about an extra field, t. It corresponds to ground state exhibiting nanoscale periodic modulation. To demonstrate stability of this phase from elastic point view, natural extension Frank energy density is proposed. built terms elements symmetry new intervene components these fields together with usual Cartesian tensors. shown that deformed for K_{22}>K_{33}. In framework model, transition between and second order finite wave vector. model does not require negative K_{33} agreement recent experimental data yield K_{33}>0. A threshold predicted twist power below no occur.