[gpaw-users] dipole corrections

[Jussi Enkovaara]

On 2011-12-15 17:13, Ask Hjorth Larsen wrote:
> On Thu, 15 Dec 2011, Sampsa Riikonen wrote:
>> Are there any plans (or maybe this has already been implemented to some
>> recent
>> development version of gpaw) to make a similar kind of correction for
>> molecules?  i.e. the potential
>> is not corrected only to the z direction but to all directions.
>
> I haven't tried this, but a simple hack would be to wrap three dipole
> corrections around each other.  They will then correct along each
> direction independently.

Hi,
I remember playing around with this kind of approach quite a long time ago. I think 
there were some numerical etc. problems, correction got expensive to calculate and 
did not produce that much improved results for systems I tried.

The file gpaw/utilities/gauss.py seems to still contain functionality which is 
required to correct potential up to arbitrary multipole moment. Basically, there is
a function "remove_moment(rho, L)" which removes multipole contributions from the 
density and returns the approriate correction to potential (for dipole term one 
needs L=1,2,3, i.e. x,y,z directions).

Maybe it would be worthwhile to play around with the correction again, is there 
some particular molecule/cluster which has very large dipole moment so that the 
correction might be useful?

Best regards,
Jussi