I am trying to understand the origin of the following expression for the reaction field (dipole [tex]\mu[/tex] in spherical cavity surrounded by medium of permittivity [tex]\epsilon[/tex]):(adsbygoogle = window.adsbygoogle || []).push({});

[tex]

\begin{equation*}

R= \frac{2 \mu}{4\pi\epsilon_0\rho^3} f(\epsilon)

\end{equation}

[/tex]

where f(\epsilon) is _not_ the Kirkwood function,

[tex]

\begin{equation*}

f(\epsilon)=\frac{\epsilon-1}{2\epsilon+1},

\end{equation}

[/tex]

but the following:

[tex]

\begin{equation*}

f(\epsilon)=\frac{\epsilon-1}{2\epsilon+4}.

\end{equation}

[/tex]

I simply can not figure out the idea behind the third expression. I have already considered [tex]\epsilon_i\ne1[/tex] for the interior of the spherical cavity, or a polarizable dipole taking as refractive index squared, [tex]n^2[/tex]=2 or 4 arbitrarily. I got many similar expressions in this way but unfortunately not the desired one. Has somebody encountered this expression already and can shed some light on its origin?

Thanks,

Joseph

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# Reaction field - not Onsager

Can you offer guidance or do you also need help?

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