Coefficiens of Gradient Terms in Landau-de Gennes Free Energy Expansion for Polymeric Liquid Crystals

We calculate the coefficients of gradient terms in Landau-de Gennes expansion for polymeric liquid crystals consisting of stiff polymers. The coefficients are expressed as a function of chain length and molecular flexibility. Using the result, we discuss orientational fluctuations in the isotropic phase and Frank's elastic constants in the nematic phase.