[Pw_forum] VCA for positional disorder

[German Samolyuk]

Dear Novendra Novendra,

The only way how to do it within pseudopotential method I found, was to
make pseudopotential with both zed and config values equal to fractional
number. For example, for Cu: zed=28.9, config='[Ar] 3d9.5 4s1.4 4p0.0'
corresponds to mixture of Cu with 1/29 vacancies.
It's not exactly the same as mixing with "empty" pspot, but more like rigid
band approximation for particular component.
If you need do do something more accurate, probably, one of the CPA KKR
packages will be more appropriate.
One more comment regarding modeling vacancies with VCA. You probably should
remember that even in closed packed structures like most of the metals
relaxation of surrounding vacancy atoms positions is significant. This
effect is not included within VCA approach.

Best,

German Samolyuk

ORNL

On Mon, Apr 3, 2017 at 2:34 PM, Novendra Novendra <novendra.andra at gmail.com>
wrote:

> Dear QE developers,
>
> I am trying to prepare input file for a system with a positional disorder.
> I have seen some example where VCA can be applied for system with
> substitional disorder, where in that case a virtual PP can be prepared by
> mixing PP of different elements. In the case of positional disorder, is it
> possible to prepare a virtual PP by mixing with an "empty" PP?
>
> Thank you,
>
> Novendra Novendra
> Ph.D Student,
> Department of Chemical Engineering & Materials Science
> University of California, Davis
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20170404/3018b9df/attachment.html>