[Pw_forum] Perturbation in electronic field

[yumin qian]

thanks for your reply

2008/10/10 Stefano Baroni <baroni at sissa.it>

>
>  On Oct 10, 2008, at 3:58 AM, yumin qian wrote:
>
>   There is one problem I am not clear about DFPT in external
>> electronmagnetic field. How to switch on the external field since the field
>> will distroy the translational symmetry(periodic boundary condition ).
>
>
> please, take the time to have a glance at:
> S. Baroni, S. de Gironcoli, A. Dal Corso, and P. Giannozzi, Phonons and
> related crystal properties from density-functional perturbation theory, Rev.
> Mod. Phys. 73, 515 (2001).
>
>
>
>
>> There a two way right now : one is add a dipole layer in vaccum layers ,
>> this method can only be used in slab calculation
>
>
>
>> the other is to add a periodic field and at the end make the periodic to
>> infinite (long wave appriximation). Vanderbilt also made a proposal using
>> the Berry phase approach,
>
>
> third, DFPT (restricted to the linear, or low-order) regime
>
>   My question is in PWSCF how the electronic field is added ,
>
>
> through either of the first two methods. the third is implemented in PHONON
>
>  and whether the method can be used in metal system ?
>
>
> homogeneous electric fields in a metal? for that a computer code is not
> enough. One should modify Maxwell's equations!
>
> SB
>
>    ---
> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
> http://www.sissa.it/~baroni / [+39] 040 3787 406 (tel) -528 (fax) /
> stefanobaroni (skype)
>
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> la pensée - Jean Piaget
>
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>
>
>
>
>
>
>
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-- 
Sincerely Y. M. Qian
Lab.of Condensed Matter Theory and Materials Computation
Institute of Physics
Chinese Academy of Sciences
Tel:  + 8610 8264 9147
E-Mail:yuminqian at gmail.com <E-Mail%3Ayuminqian at gmail.com>
P.O.Box 603   Beijing 100190
China
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