Interaction energies in nematogens

Abstract

The effect of steric exclusions between rods in correlating positional with rotational hinderances is used to calculate the mean field a rod sees in a fluid of other rods with which it interacts via anisotropic dispersion forces. The resultant potential involves all Legendre polynomials even within the dipole-dipole approximation. It is also possible to see how specific forces could be incorporated into the derivation to give the often anomalous results seen in Raman scattering. The magnitude of the potential is also estimated using absorption, scattering, and equation of state data. The resultant characteristic energy is somewhat smaller than that required by a recent theory of Flory and Ronca which contains both steric and dispersion effects, and is much smaller than that required by the Maier-Saupe approach which takes no account of steric influences. © 1980 American Institute of Physics.