[Pw_forum] polarization calculation for system of surface states.

[Stefano Baroni]

On Oct 18, 2006, at 3:05 PM, lan haiping wrote:

> Hi, All!
>
>    I performed a calculation on a single layer of H1Ti3O7, i.e .a  
> proton deficiency system, which  would made system be metallic due  
> to surface states.   I wanna ask a stupid question: is it possible  
> to use berryphase or DFPT method to examine the polarization of  
> this system ?

let me try a studpid answer:
1) D=E+4\pi P
2) D=0 => E=-4\pi P
3) P /=0 => E /=0, which cannot be in the bulk of a conductor

does the above make ansy sense?

> i had read some related publications, but didnot reach most idea  
> of  modern theory of polarization.
> when i run a ph.x calculation of this system , the programme  
> complained about  its metallic.

the reason of the complains does not lie in any sophisticated "modern  
theory of polarization", but just in elementary (and old!)  
electrostatics..

Hope this helps - Stefano

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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