[Wien] Obtaining the Reference Energy for Calculated Band Structure

[Craig Plaisance]

I know that Wien references all calculated energy levels to the average 
lattice potential, but is there a way that I can obtain this average 
lattice potential relative to the lattice continuum threshhold (the 
potential at infinite distance from the crystal plus the surface 
potential barrier).  I am probably not explaining this well, so I will 
elaborate by giving an example of why I want this information.  Suppose 
I have a lattice for which I have calculated the band structure using 
Wien and I want to compare this bandstructure to the atomic energy 
levels of a dopant atom (which are calculated relative to the potential 
at infinite distance from the atom using a package such as Gaussian).  
In order to make this comparison, I need to shift the lattice energy 
levels by an appropriate amount so that they have the same reference as 
the atomic levels.  How do I get the value for the energy shift?  Thanks.

Craig Plaisance
Louisiana State University
Baton Rouge, LA