Clausius external fields

The Born model with integral or partial charges assumes that the ions have zero polaris-ability. This is reasonable for small cations such as Li" or Mg + but can introduce significant errors for other systems. One pxropjerty that clearly demonstrates this is the high-frequency dielectric constant. At a suitably high frequency only the electrons can keep up with the external field and the dielectric constant is given by the Clausius-Mosotti relationship ... 

The linear polarizability, a, describes the first-order response of the dipole moment with respect to external electric fields. The polarizability of a solute can be related to the dielectric constant of the solution through Debye s equation and molar refractivity through the Clausius-Mosotti equation [1], Together with the dipole moment, a dominates the intermolecular forces such as the van der Waals interactions, while its variations upon vibration determine the Raman activities. Although a corresponds to the linear response of the dipole moment, it is the first quantity of interest in nonlinear optics (NLO) and particularly for the deduction of stracture-property relationships and for the design of new... 

Now let us calculate the alteration of the potential energy U in the case of polarisation by an electric field 2 or. The orientation field Bor depends on the external electric field E which is given by Clausius-Mossotti EOT = (e + 2)/3 E or with somewhat better results by Gnsager32 ... 

The Clausius-Mossotti equation is based on the assumption that the polarization induced by the external electric field is proportional to the field strength, or that... 

---