Take the 2-minute tour ×  I am currently building a theoretical
model where charges of opposite signs are created by pairs and
then diffuse and are drifted by an electrical field. I am taking
this along a single so far, for simplicity. The object I'd like
to arrive at the end is a local (density of) polarization, and
not the global one (because the diffusion gives me two
gaussians, spreading in time and drifting in opposites ways. But
when I try to come up we've an expression for this polarization
field, nothing pertinent comes out: if I look at one point and
compute the barycenter of the charges from there, I get the same
expression no manner where it is because of the global charge
neutrality; and when I think about only computing charges in a
small area about the point, I can't guarantee the neutrality of
the charges inside this area (and so polarization is irrelevant
in there). I am wondering if it's not because there is not more
information than the one given by the separation of the two
charge distribut