[CP2K:10470] Band structure calculation with external periodic potential

[Matt W]

Look in qs_external_potential.F for the code.

It is quite flexible. You can supply a function in analytic form in this 
section 
<https://manual.cp2k.org/cp2k-5_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/EXTERNAL_POTENTIAL.html>. 
You should be able to set up a periodic external potential without any 
coding, I think.

Matt  

On Saturday, June 30, 2018 at 8:00:12 PM UTC+1, NGastaPooh wrote:
>
> Hello Matt,
>
> Thank you very much for your answer. I want to periodically shift 
> electronic charge density throughout a periodic solid to create a charge 
> density "wave". The next step would be to observe the effect of such 
> density change on a band structure of the solid. 
>
> As far as I understood from your answer, the only way is to go with 
> external potential. Does it sound right? If so, could you please direct me 
> to the source file for it?
>
> Thanks in advance.
>
> Best regards,
> Roman Dmitriev.
>
> On Jun 30, 2018, at 10:42 AM, Matt W <matt... at gmail.com <javascript:>> 
> wrote:
>
> Hi,
>
> there are, in principle, several ways of applying an electric field. The 
> only way that makes proper sense for a periodic solid is the periodic 
> efield 
> <https://manual.cp2k.org/cp2k-5_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PERIODIC_EFIELD.html>
> .  I would be (very) surprised if it works with k-points. The main methods 
> are in qs_efield_berry.F. 
>
> See 
>
>  Stengel, Massimiliano; Spaldin, Nicola A.; Vanderbilt, David. 
>  NATURE PHYSICS, 5 (4), 304-308 (2009). 
>  Ab initio molecular dynamics in a finite homogeneous electric field
>  Electric displacement as the fundamental variable in
>  electronic-structure calculations.
>  http://dx.doi.org/10.1038/NPHYS1185
>
> and
>
> Zhang, Chao, Jürg Hutter, and Michiel Sprik. "Computing the Kirkwood 
> g-Factor by combining constant maxwell electric field and electric 
> displacement simulations: application to the dielectric constant of liquid 
> water." *The journal of physical chemistry letters* 7.14 (2016): 
> 2696-2701.
>
> There is also a non periodic version that might be easier to follow 
> (efield_utils.F) and a general external potential that could be applied. 
> Depends what you want to do.
>
> Matt
>  
> On Thursday, June 28, 2018 at 11:17:33 PM UTC+1, NGastaPooh wrote:
>>
>> Dear All,
>>
>> I need to utilize the ability of CP2K to subject the electrons to an 
>> externally imposed electric 
>> field but am not sure as to exactly how this is implemented in the code. 
>> I would greatly appreciate 
>> it, if anyone could provide me with some details or direct me to the 
>> sub-routine that accounts for the external potential implementation.
>>
>> I also have a separate question: what are the energy units in 
>> BAND_STRUCTURE routine output file? 
>>
>> Thank you in advance.
>>
>> Best regards,
>> Roman Dmitriev
>>
>
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