[Pw_forum] How to select unit cell for optimization calculation?

[Youssef]

Dear Max,

The decision return to you, you shouldn't to choose the minimal value 
of course, but the value beyond which the criteria doesn't change 
significantly and the relative differences are accepted with respect to 
computational cost and accuracy.
You've do the same thing with energy but as you noticed the decision 
using force is more easy.

Youssef Aharbil,
Laboratory of Physics and Chemistry of Materials
Faculty of sciences Ben msik, Casablanca
Morocco


On Fri, Jul 10, 2015 at 10:15 PM, max <aquiles011 at gmail.com> wrote:
> Dear Youssef,
> 
> I attach a pdf with result of my last calculations (data and graph).
> 
> Ecut vs Etotal and Ecut vs Total force.
> 
> If the rules about 1mRy for energy and 1.0D10-04Ry/au per atoms are 
> myths. How can I choose the correct value for convergence?
> 
> The minimun value of total force is 0.004268 Ry/au for Ecut = 75 Ry 
> can I choose this value for convergence?
>  
> -- 
>      Máximo Ramírez
>      Physics Degree
>      Universidad Autónoma de Santo Domingo
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