[Pw_forum] Convergence issues with Bulk Magnesium

[Lorenzo Paulatto]

On Thu, Jul 5, 2012 at 9:30 PM, MMS <mm2422 at cornell.edu> wrote:

> Mg 24.305 Mg.pz-n-vbc.UPF
>

This pseudopotential is actually norm.conserving (there is an error in the
web site, but you can check directly in the UPF file yourself). So you do
not need to specify ecutrho.


>
> Now, I tried varying the degauss values and even tried increasing the k
> points, but I still see the same behavior. Can I get some pointers in this
> regard?
>
>
This fact would suggest that the pseudopotential has a ghost state at very
high energy. This is not necessarily a problem, every pseudo do, i.e. no
vbc pseudopotential is equivalent to a real atom up to infinite energy. In
your case the energy is converged at 30 Ry; at 60ry there is some problem.

Try again without ecutrho to see if you can get a clear convergece, if you
do not find clearly a convergence energy I suggest you use another pseudo

-- 
Lorenzo Paulatto IdR @ IMPMC/CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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