[gpaw-users] dipole corrections

[Sampsa Riikonen]

Dear List,

I am a novice here..

.. so nice to meet you all.

My question concerns the dipole corrections in gpaw.

The module can be found here:

https://wiki.fysik.dtu.dk/gpaw/epydoc/gpaw.dipole_correction.DipoleCorrection-class.html

Does this module implement the dipole corrections in a similar way to..?

dx.doi.org/10.1103/PhysRevB.59.12301

The electrostatic potential is forced to zero on the (z) boundaries.  
This is equivalent to
adding something to the charge distribution.  This "something" is then 
eliminated once
the potential has been calculated using the poisson equation, by 
subtracting a linear
V(z) term from the potential.

Then gpaw is actually calculating the potential using "open" boundary 
conditions and there
is no problem with anything, i.e. it is exact.

Am I right..?

However, in the following post

https://listserv.fysik.dtu.dk/pipermail/gpaw-users/2010-April/000101.html

it is said that ..

"Atomic forces may be a bit off for dipole-corrected calculations"

Is this still a problem...?  Why the forces "may be a bit off" ?

And continuing the same theme..

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.

Kind Regards,

Sampsa