[QE-users] a problem related to the electric field calculations

[Rostami Samare]

Dear Mostafa,

Thank  you a lot for your comments and suggestions.
I will test your suggestions and hope the problem will be fixed.

I've already relaxed the structure in the zero field and
checked the state of the electrons by plotting DOS.

Kind Regards,

Samare
ICTP


> Dear Samare,
>
>
> You are performing 'scf' calculation for Ti-doped Fe2O3 under electric
> field.  This gives only the electron's response to the field.  If you are
> interested in ions response (and in fact the ion-electron response) , you
> may need to use 'relax'. Of course make sure to relax the zero field
> Ti-doped hematite first before you start electric field calculations.
>
> For plain PBE for Ti, you may end up with a metallic solution. Ti wants to
> be in oxidation state +4 and the leftover electron may (or may not) spread
> over the whole cell causing metallic solution. In this case of metallic
> solution, electric field calculations will not converge.  You may check
> the
> state of the last electron by plotting DOS  or visualizing the defect
> state
> in 3D.
>
> Also, the field is large. Add it gradually as I described in my previous
> post.
>
> I never used the pseudos you are using. But the ones here:
> https://www.materialscloud.org/discover/sssp/table/efficiency
> are usually very good. Although Fe pseudo is very computationally
> intensive.
>
> If you change the occupations to 'smearing' and add a tiny smearing (0.004
> Ry), this can accelerate the convergence. Again this is after you make
> sure
> that the last electron in Ti-doped hematite is not leading to a metallic
> solution.
>
> Hope this helps
>
>
> Regards,
> Mostafa
> AUC
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