[CP2K:8947] dielectric function calculation

[Matt W]

Hi,

there are going to be several competing / contradictory ways of doing these 
calcs.

I have only done them for a non-periodic system (slab), then you can apply 
the external field, as you are doing, and print of the density as a cube 
file. You can relate the change of density with applied field to get the 
dielectric 'constant'.

For a periodic system, you would need to use a periodic electric field and 
presumably also look at the density response and use electrostatics.

I haven't used the new implicit psolver method, my feeling is that the 
dielectric there is more likely to be an applied boundary condition, rather 
than an output, but it is very flexible, so maybe it can be made to do what 
you want. It will only be activated if you use the implicit solver, which 
is probably why you see no output.

Matt


On Monday, April 24, 2017 at 2:35:15 PM UTC+1, Fernan Saiz wrote:
>
> Hi,
> Thanks for the reply. In this case, I guess CP2k should be able to write a 
> CUBE output file with epsilon(x,y,z) once a external potential is applied, 
> shouldn't it?
>
> I can implement an external potential by writing in the input file: 
>
> &FORCE_EVAL
>   &DFT
>     &EXTERNAL_POTENTIAL
>       FUNCTION (A/B)*X
>       PARAMETERS A B
>       VALUES [eV] 5.0 [angstrom] 1000.0
>     &END 
>   &END 
> &END 
>
> But to print the dielectric constant epsilon(x,y,z) in CUBE files, I am 
> writing the following commands:
>
> &FORCE_EVAL
>   &DFT
>     &PRINT
>
>       &IMPLICIT_PSOLVER
>         &DIELECTRIC_CUBE
>           &EACH
>             JUST_ENERGY 1
>           &END EACH
>           FILENAME diel/data_diel
>         &END DIELECTRIC_CUBE
>       &END IMPLICIT_PSOLVER
>
>     &END 
>   &END 
> &END 
>
> Unfortunately, this second paragraph of commands does not write anything 
> in my working directory. Am I using the wrong commands?
>
> Regards, 
>  - Fernan
>
> On Tuesday, April 18, 2017 at 3:09:50 PM UTC+1, jgh wrote:
>>
>> Hi 
>>
>> I think all the parts needed to do such a calculation are available, 
>> but there is no such keyword to let the code do it automatically. 
>>
>> regards 
>>
>> Juerg 
>> -------------------------------------------------------------- 
>> Juerg Hutter                         Phone : ++41 44 635 4491 
>> Institut für Chemie C                FAX   : ++41 44 635 6838 
>> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
>> Winterthurerstrasse 190 
>> CH-8057 Zürich, Switzerland 
>> --------------------------------------------------------------- 
>>
>> -----cp... at googlegroups.com wrote: -----To: cp2k <cp... at googlegroups.com> 
>>
>> From: Fernan Saiz 
>> Sent by: cp... at googlegroups.com 
>> Date: 04/15/2017 12:06PM 
>> Subject: [CP2K:8947] dielectric function calculation 
>>
>> Hello all, 
>> I would like to ask if CP2k is able to calculate the high-frequency 
>> dielectric function epsilon(z) as a function of a given direction z as 
>> formulated by Fu. et al. PRB 57, 6967 (1998). As a further reference, the 
>> all-electron code CRYSTAL14 has it implemented using a finite field 
>> perturbation method. 
>>
>>  Thanks, 
>>  - Fernan Saiz, PhD 
>> Department of Chemistry 
>> Imperial College London 
>>
>>
>>
>>
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>>
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