Linearized planar screening solution
= Linearized planar screening solution
{title2=$\psi=\zeta e^{-\kappa x}$}
For $|e\psi|\ll k_BT$, $\psi\prime\prime=\kappa^2\psi$ with $\kappa^2=2e^2n_0/(\varepsilon k_BT)$ for a symmetric monovalent salt with per-species reservoir <density> $n_0$. The half-space solution with $\psi(0)=\zeta$ and vanishing bulk potential is $\zeta e^{-\kappa x}$. If <density> denotes the sum of species, the written factor of two changes.