# [Pw_forum] total charge

Giuseppe Mattioli giuseppe.mattioli at ism.cnr.it
Wed Jun 19 12:59:47 CEST 2013

```Dear M.Kamaraj

>          1. total charge of the system

This is the sum of all the (core+valence) electrons, of course...

>          2. charge of  each  B and N atoms in my system

This is a very different problem, because there is no univocal method to estimate such quantities. The projwfc.x post-processing code provide an
estimate of Lowdin charges, and it could be useful for your purpose. If you want a more "fashionable" method, you may try to use the cross-platform
Bader integrator (which is not part of the QE distribution), which works well only with PAW pseudopotentials.

>          3. how much charge is transferred  between B and N atoms

It depends straightforwardly on 2... And the result depends strongly on the partitioning scheme (Lowdin, Mulliken, Bader, ...)

HTH

Giuseppe

On Wednesday 19 June 2013 12:31:13 Kamaraj M wrote:
> Dear QE users,
>     presently i am working with BN sheet, for that  i want to calculate
>  the
>          1. total charge of the system,
>          2. charge of  each  B and N atoms in my system (if i know this, i
> will get the answer for the  first question)  and
>          3. how much charge is transferred  between B and N atoms
> its possible to calculate the  above parameters with QE?  if yes,  how can
> i calculate? send me any link or  examples  which used to calculate the
> above parameters. i searched in forum, but i did not get the  answers.
>

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