Molecular Theory of Orientational Fluctuations and Optical Kerr Effect in the Isotropic Phase of a Liquid Crystal

By use of Kubo's statistical formalism, we show that the orientational fluctuations of interacting molecules are responsible for both the narrow central component and the broad Rayleigh-wing component in the light-scattering spectrum of a liquid crystalline material. The same formalism also describes the optical Kerr effect. We also point out the difference between the microscopic and the macroscopic order parameters.