[Pw_forum] ion problem

[Stefano de Gironcoli]

Unless you put some constraint the code will distribute the charge 
density so as to minimize the total energy. If the atoms behaves as ions 
in your cluster this will be automatically found by the code.
A way (one of the many arbitrary ways) to measure this atomic charge is 
to project the wfc on atomic orbitals and counts how many electrons are 
projected on each atom... this is done by projwfc.x in the PP directory.
If you want to force the system to do something else w.r.t. what it 
would do automatically you need to add some constraint. For instance in 
a non collinear magnetic calculation one can constraint the size of the 
atomic magnetization, its direction or one of its commponents. In the 
cvs version magnetization size can be constrained also in the collinear 
case.
Currently there is no constraint on the atomic charge but using the 
constrained_magnetization part as template should not be too difficult 
implement such a feature.

Hope this helps,

Don't forget to sign your posts including your affilation.

Stefano de Gironcoli, SISSA and DEMOCRITOS

Rudra Banerjee wrote:
> dear PWSCF users,
> I am new to pwscf and stuck in a question.......is there any way to 
> put anion   or cation    as a unit?the total cluster is charge less 
> but have two different types of ion.......can anyone tell me what to 
> do in this situation?
> Regards
>  
> -- 
> Rudra
> Have a Nice Time
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