[Pw_forum] How to generate pseudo of atoms on a partially occupied position using virtual.x ?

[Stefano Baroni]

Dear Ruizhi: the virtual crystal approximation is definitely not the  
way to go to study defective systems. The VCA applies to those cases  
where the different atoms in the disorder sublattices have rather  
similar properties. This not your case, where an atom is certainly  
not similar enough to "no atom". Cheers - Stefano Baroni
On Jan 29, 2007, at 3:35 AM, ruizhi zhang wrote:

> Dear all：
>
> I want to study a system in which oxygen atoms are on a partially  
> occupied position. So I need to generate a 'virtual' potential of  
> oxygen using Virtual Crystal Approximation . As has been discussed  
> in the forum, using virtual.x in upftools/
> new pseudopotential = (1-x)V1+xV2
> However, in my case V1 is pseudo of Oxygen and V2 is a vacancy, and  
> I do not know how to deal with it.
> Can I generate a pseudo of Oxygen specifying the Z valance=0 ?  
> (Maybe it is a stupid idea) and use this as the pseudo of vacancy?
>
> Thank you very much in advance.
>
> Best regards
> ruizhi zhang
>
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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