[Pw_forum] About ZnO Slab

[Giuseppe Mattioli]

Dear Bipul
I've tried to run your input file, and I suppose that your calculation does not converge because of the strong vertical dipole related to the 0001 
wurtzite slab, which you could try to visualize by calculating the planar average of the KS potential. My suggestion is to increase the vacuum to 
decouple the images, but it could be not sufficient, because the dipole should be quite strong. This is also a good reason for strange work-function 
numbers. AFAIK the polar ZnO surfaces are rarely exposed in real systems. The most stable and common surface is the nonpolar (10-10) one, which does 
not usually show any convergence problem. Buy you know what surface you need...
HTH
Giuseppe

On Friday, May 08, 2015 12:29:25 AM Bipul Rakshit wrote:
> Dear users,
> I am doing ZnO slab calculation with 12 Double layer of ZnO. Since ZnO is a
> wide band-gap material, so I am using occupation=fixed. I attached my input
> also.
> But why the calculation is not converging?
> 
> But when I am using occupation=smearing, it do converge. But it gives a
> work function of 3.47 eV after applying the dipole correction.
> 
> So what mistake I am doing?
> 
> Please help me in this regards

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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
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