[Wien] Reg. Rkmax and K point

[Santhy Jaiker]

Dear Stefaan, 
  Thanks for your immediate reply.  But i am not able to understand the statement, "Roughly double the number of k-points at each step (doubled in the IBZ [=nr. of lines in case.klist], not in FBZ [=input for kgen])."  kindly elaborate the above sentence.
  
Regards,
  Santhy Jaiker


Stefaan Cottenier <stefaan.cottenier at fys.kuleuven.be> wrote:
  
> For finding the suitable RKmax and K point for a transition metal or 
> compound, i am running the SCF calculation with RKmax range 7 to 10.5 
> with step of 0.5.
Your lower and higher ends are a bit high. Start at 5.5, and stop when 
you see no further evolution (rarely beyond 8.5).
> Similarly, For k point with increment of 1000 or 2000
Also here you're taking too many steps. Roughly double the number of 
k-points at each step (doubled in the IBZ [=nr. of lines in case.klist], 
not in FBZ [=input for kgen]).
> upto 0.00001Ry of energy convergence. Simultaneously i am looking the 
> other parameters like CTO, Fermi energy, DIS... that the energy is 
> properly converges or not.
This criterium might be a bit strong for the sake of testing. Does 
anything meaningful changes in observable quantities if you converge 
only up to 0.000x?)

You are doing it the right way: first doing these tests before you go on 
with the more interesting work. Congratulations! Many others carelessly 
skip this part. But don't overshoot in the other direction...

Stefaan
> But it takes very long time, before going to volume optimization or 
> mini. If there is any other shorter method is available, to find the 
> suitable RKmax and K point.
> 
> Thanks in advance.
> 
> Regards,
> Santhy Jaiker
> 
>
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