[Pw_forum] polarization calculation for system of surface states.

[lan haiping]

thank you, stefano.
my confusion may be due to this surface states.
though there are some surface states , i thought it should be an insulator
due to large bandgap.  Is it mean that we should take systems with surface
states as metal?

regards,
hai-ping


On 10/19/06, Stefano Baroni <baroni at sissa.it> wrote:
>
>
>  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)
>
> Please, if possible, don't  send me MS Word or PowerPoint attachments
> Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html
>
>
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20061019/5d9582f5/attachment.html>