Diffusion-distance convention
= Diffusion-distance convention
{title2=$\ell\sim\sqrt{Dt}$}
The scale $\sqrt{Dt}$ characterizes <diffusion> over time $t$. For unrestricted isotropic <diffusion>, the rms displacement in one coordinate is $\sqrt{2Dt}$ and the total three-dimensional rms displacement is $\sqrt{6Dt}$. Stating the convention avoids spurious disagreement over a numerical prefactor.