Kirkwood model for pure polar fluids of non-polarizable molecules

Abstract

In this paper, we guide the reader to obtain the Kirkwood equation for pure polar fluids of molecules with negligible polarizabilities. Such equation relates the dielectric constant of the fluid, its density and its temperature to the permanent dipole moment of its constituent molecules, and also involves a dimensionless factor g – known as Kirkwood correlation factor – whose value is an expression of the correlation between the orientantions of the molecules of the fluid, in the situation of zero external electric field. Along the way, we seek to show as much as possible the similarity between the Kirkwood model and the Onsager model applied to pure polar fluids of non-polarizable molecules (or with negligible polarizabilities).

Keywords
Kirkwood model; dielectric constant; dielectrics