Dipole Moments, Polarizabilites and Hyperpolarizabilities

Neutral molecules can be represented as systems of electric charges distributed in space. Positive charge is concentrated in the atomic nuclei, and negative 

Wolfsberg et al., Isotope Effects in the Chemical, Geological, and Bio Sciences, 389 

12 Isotope Effects on Dipole Moments, Polarizability, NMR Shielding, and Molar Volume 

The discussion to this point has not considered the effect of an externally impressed electric field. When a molecule is placed in an electric field the energetics of the interaction are expressed, 

In Equation 12.2 symbolizes the total energy and E the electric field strength. The subscripts indicate the derivatives are evaluated at E = 0. The dipole moment, p, is given as 

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