Susceptibility and Local Field Effect

OPTICAL DIELECTRIC CONSTANTS AND REFRACTIVE INDICES 3.4.1. Linear Susceptibility and Local Field Effect 

The optical dielectric constants originate from the hnear polarization P generated by the incident optical field Eop on the nematic hquid crystal  

Here X is the linear (sometimes termed first order ) susceptibility tensor of the 

Most of the approaches used to obtain the local field correction factor are based on the Lorentz results, which state that the internal field (i.e., the local field as experienced by a molecule E ° in a solid) is related to the applied field by 

In particular, Viiks ° analyzed experimental data and proposed that the local field in an anisotropic crystal may be taken as isotropic and expressed in the form 

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