"quadrupole" corrections for non-neutral systems?

[Matt W]

You might want to output the electron density on a 3D grid

https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/E_DENSITY_CUBE.html

Probably you want to do this for the ideal and defect system, and subtract 
the two densities (https://www.cp2k.org/tools:cubecruncher might be useful).

Hopefully this would give you a fairly localised density that you can then 
calculate the dipole / quadrupole moments of. If it isn't localised, then 
probably the correction schemes break down anyway ...

Matt 

On Saturday, September 9, 2017 at 1:25:56 PM UTC+8, Peng wrote:
>
> Hi all,
>
> I'm wondering if it's currently possible with CP2K to apply a correction 
> for
> non-neutral periodic system as in Eq. 14 of G. Makov & M. C. Payne, Phys 
> Rev B
> 51 4014 (1995), which involves determining the center of charge as well as 
> an
> integration: \int_cell dr^3 \rho(r) r^2. I assume the first part is just 
> related
> to the total system dipole calculated with respect to the origin of the
> coordinate system (CP2K_INPUT / FORCE_EVAL / DFT / PRINT / MOMENTS / 
> REFERENCE =
> 0), but how should I go about computing the integral? If it's not directly
> supported, can someone please give some quick pointers on where and how to 
> hook
> into the each MD step to implement this? Any suggestions would be really
> helpful. Thank you very much!
>
> Best regards,
>
> Peng
>
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