[Wien] vacuum thickness

[Stefaan Cottenier]

> There is one more question: to compare the
> work function WF = (v0c or v5c) - :FER.  can i just do a quick
> calcution,i.e.a few K-point(for example only 4 points for ten atoms)? I
> wonder how many k-points should i use to get the accurate WF quickly?

No idea. :FER is not very sensitive to the k-mesh. I assume the same is true 
for v0c. But I don't know for sure what's the accuracy in the WF that should 
be obtained. 3 digits looks reasonable (but that's partly a guess). I would 
test how many k you need to get :FER stable up to 3 digits and then proceed 
with that mesh. 

Stefaan