Using a mean-field theory, a twist-bend nematic (NTB) phase has been described. In addition to second-order Legendre polynomial term, the chiral interaction potential includes third-order Legendre polynomial term also. It considers the coupling between a nematic director and a pitch axis of the NTB phase. The distortion free energy, order parameter for twist-bend nematic, and orientational distribution function in equilibrium state have been calculated. Based on the free energy minimization, we obtain that the inclusion of third-order Legendre polynomial term in interaction energy makes NTB phase more stable.

中文翻译：

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扭弯向列相：三阶勒让德多项式项在手性相互作用势中的作用

使用平均场理论，已经描述了扭曲弯曲向列 (NTB) 相。除了二阶勒让德多项式项外，手性相互作用势还包括三阶勒让德多项式项。它考虑了向列导向器和 NTB 相的螺距轴之间的耦合。计算了扭曲自由能、扭弯向列的有序参数和平衡态的取向分布函数。基于自由能最小化，我们得到在相互作用能中包含三阶勒让德多项式项使 NTB 相更稳定。