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[verstraete@pcpm.ucl.ac.be]

Hello all,

concerning charged systems, Abinit is still pretty bad. It only adds a 
jellium background (ie neglects the G=0 component), and does (to my 
knowledge) no further Makov-Payne type correction. You can do some 
correction by hand if you know the potential or if you calculate several 
different charge states.

There are several articles that claim that the MP correction is
insufficient and doesn't exactly cancel the multipolar interaction between
cells. e.g. see "Charged local defects in extended systems" Schultz PA
PHYSICAL REVIEW LETTERS 84 (9): 1942-1945 FEB 28 2000

There is a lot of litterature debating this, if you look at articles 
citing MP.

Matthieu

On Tue, 24 Feb 2004, Vincenzo Fiorentini wrote:

> I don't know whether abinit takes care of this, but the standard way
> to proceed for charged point deefcts is to assume a neutralizing
> background and sum to the energy thus obtained a correction 
> q^2 A/(2 eps L), in Ha, q being the charge, eps the dielectric
> constant (static if you relax ions), L the lattice constant of your
> cell and A the Madelung constant of the superlattice. You find a
> description of  this in Makov and Payne, in PRB around 1995. The
> correction is for   monopole-monopole interactions; you may have
> dipoles to take care of, also discussed in the same paper. Note that 
> a recent paper (PRL 03) by SH Wei questions the usage of these
> corrections. 
> 
> best - Vincenzo Fiorentini
> 
> 
> >  dealing with charged systems
> 

-- 
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Matthieu Verstraete               mailto:verstraete@pcpm.ucl.ac.be 
PCPM, Boltzmann, pl. Croix du Sud, 1            tel: 010/ 47 33 59
B-1348 Louvain-la-Neuve  Belgium                fax: 010/ 47 34 52