Solute Orientation The Shape Model

It has recently been suggested that two main ordering mechanisms are responsible for the orientational ordering of the solutes in liquid crystals. The potential of mean torque may be approximated by 

The first term results from the long-range interaction between the molecular quadrupole moment of the solute and the average electric field gradient Fafs in liquid crystals [4.30]. It is given by 

Charvolin and B. Deloche, The Molecular Physics of Liquid Crystals, edited by G.R. Luckhurst and G.W. Gray (Academic Press, New York, 1979), Chap. 15. 

Statistical Mechanics of Chain Molecules (Interscience, New York, 1969). 

Luckhurst, Nuclear Magnetic Resonance of Liquid Crystals, edited by J.W. Emsley (D. Reidel Publishing Co., Dordrecht, 1985), Chap. 3. 

---