[Pw_forum] forces_bp_efield.f90

[Stefano Baroni]

Dear Q.J. Wang,

please, consider that the probability of getting a polite and informative answer to your posts is fairly independent of the number of times you send your post. It is my past experience that the probability of receiving a rude and uninformative answer, instead, increases exponentially with the number of posts. The larger the number, the higher the chance, the ruder and less informative the answer.

This being said, here is the answer. Hope it is polite enough, even though it may be not too informative.

I do not know what "forces_bp_efield" does. If, as it seems, it deals with an applied electric field, it seems natural to me that it only works (it should only be used) for insulators. In a metal an applied electric field is completely screened by conduction electrons.

Stefano

On Dec 7, 2009, at 2:28 AM, Q.J.Wang wrote:

> Dear all
>      In the forces_bp_efield.f90,one part of code is as following:
>      !  --- Check that we are working with an insulator with no empty bands ---
>    IF ((degauss > 0.01d0) .OR. (nbnd /= nelec/2)) &
>         WRITE (stdout,*) 'PAY ATTENTION: EL FIELD AND OCCUPATIONS'
> So I want to know the forces_bp_efield.f90 only fit to insulator ? If my system is half metallic ,can I use this code to relax ? If my system have odd electrons ,how to set it ?
> 
> 
> 
> --
> Best regards
>  
> Q.J.Wang
>  
> XiangTan University
>  
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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