[Pw_forum] Convergence issues with Bulk Magnesium

[MMS]

Dear Giovanni,

Thanks a lot for helping me out. With regard to your suggestions

1. The calculations converge w.r.t nbnds. The energy values for
nbnds=10 and nbnds=40 are identical with ecutwfc=50 and ecutrho=500.
2. With regard to degauss value how should I perform the convergence?
   Should I just increase it from say 0.02Ry to 0.06Ry and study the
energy values?
   While searching the forums I came across this thread
   http://www.democritos.it/pipermail/pw_forum/2008-January/008157.html
   which tells me that I should find a k-point set and a smearing
value that kind of complement each other. So how do I do that?
3. I have a question regarding k point test.
   I always thought that the calculations were performed per k point
and then summed up to find the total integral value.
   So, is it not enough to have a moderate sized k point mesh
initially to test out the convergence of the
   ecutwfc values and then followed by a k point convergence test?

4. Lastly, I find ecutrho every time I update ecutwfc when I had
formed that table.

I once again thank you for helping me out.

Regards

Meenakshi Sundaram
Graduate Student
Mechanical and Aerospace Engg.
Cornell
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