[Pw_forum] Convergence test on big model

[Yangchuan Li]

Hi everyone,

I want to ask whether a converged Ecut and smearing width can be used in
another model. I have a big model (functionalized carbon nanotube) and it's
time-consuming to do scf calculation. I notice Stefano mentioned that Ecut
is not strongly depended on particular configuration. (In topic Technique
for converging Ecut and K-points?)

So can I used small model like diamond, nitrogen gas to do convergence test
and then use the preferred parameter in my big model? Why I can or can't do
that?

Also, if the dimension of the system is big. Is it necessary to select a
very dense k-mesh? Is there a preferred k-point density in reciprocal space?

Thank you for your time. Any comment will be appreciated.

Yangchuan Li
UT Austin | ME
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