This is a manufactured solution for the nonlinear Poisson. The
analytic solution is given by:

V(x) = 0.3 erfc[20000(x-0.00025)]-0.3

The geometry in the exodus file should be 5 microns in x [0-5um]. The
size in the y direction is not significant as this is a pseudo 1D
solution.

Boundary conditions should be set to 0.3 at x=0 and -0.3 at x=5um. 

The doping acts as the "source" for this problem and it is given by an
analytic function. However, since the code doesn't support a general
function for doping specification the approach taken here was to
sample the analytic function and output the data to a file which is
then read into Charon2. For simplicity a Gnumeric spreadsheet,
nlp-mms-doping.glh.1.gnumeric, is included where the analytic doping
can be generated at discrete points and then output to an ASCII data
file for input into the code.

Note that the derivation and more detailed information for this MMS
can be found in the associated Mathematica notebook file:

    nlp-mms-derivation.glh.1.nb
