Permanent Dipole and Molecular Ordering

The fact that liquid crystal molecules themselves could possess a permanent dipole moment (even though the bulk dipole moment has vanished) has been taken into account in the treatment of Saha and Wong of the molecular correlation effects in third-order nonlinear polarizabilities. Their calculations show that, in general, the experimentally measurable third-order nonlinear polarizabilities, jyyyy, and y for example, are related to their microscopic cormterparts and Yy by tte following relationships  

Yiso KYiiII + Y2222 Y3333 2Yi122 Y3322 2Y331i) 

This follows from the definition for the orientational distribution function f(0)  

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