[Pw_forum] different k point in scf and nscf

[xirainbow]

Dear Amene Nouri :
Usually, the k-mesh used in nscf is bigger than that in scf.
In scf calculation, the difference between input and output electron density
must be less than a small value.
However, the electron density obtained in scf is used and maintained in nscf
calculation. That means electron density in nscf calculation is  not
self-consisent.
As mentioned above, nscf is not not self-consisent. Therefore, nscf can save
a lot of time.

If your calculation is converged, the nscf and scf would give the same
result.

On Fri, Jul 23, 2010 at 1:28 PM, Amene Nouri <a.nourmohammadi at yahoo.com>wrote:

>
>
>
>    Hello all
> In scf calculation we choose a k point for sampling Brilouin Zone for
> example n1*n1*n1.
> In next step in nscf calculations we choose another k point for example
> n2*n2*n2.
> Do not we use the results of scf calculation in nscf calculation?
> why k points can be different?
> which results of scf calculation is used in nscf step?
>
> Thanks in advance.
>
>
>
>
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-- 
____________________________________
Hui Wang
School of physics, Nankai University, Tianjin, China
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