Electric multipole moment fluctuations in polar liquids (original) (raw)

A general expression for the distribution of the fluctuating 2 ᐉ -pole moment M ᐉ of a spherical sample of dielectric material is derived on the basis of dielectric theory combined with statistical mechanics. The formulas are compared with results from computer simulations of a weakly coupled Stockmayer fluid and the agreement is shown to be excellent. Furthermore, we calculate the size of the coupling, quantified through the free energy of solvation A solv , of the fluctuating electric moments to a surrounding dielectric medium. It turns out that the contribution to A solv from each fluctuating electric moment actually increases with increasing order ᐉ of the moment, resulting in a formally infinite free energy of solvation. We also present a correction to A solv for molecular media, which shows that the molecular nature of the surrounding medium effectively suppresses the divergence in the solvation free energy.