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I am trying to get the "VASP theory value" for the lattice constant for hcp Mg. My plan is to do it with "production level" convergence. So first I found that a 16x16x16 Monkhorst-Pack grid is converged and now I am going to do the energy cut off convergence before I start searching for the optimal lattice parameter.

I got to thinking... since I am only doing energy cut off convergence now and not moving the ions at all I can use ISMEAR=-5. But later I might want to do be able to have ISMEAR = 1 when I am searching for the optimal lattice parameter. Will my energy cut off that I found with ISMEAR=-5 still be valid when I move on to searching for the optimal lattice parameter and set ISMEAR = 1?

The answer would be nice... but a few sentences on the thought process that leads to the answer would be really really great.

Regards,
vasp_user

Looks like ISMAR=-5 should be used with a gamma centered k-mesh.

[quote author=-5 still be valid
[/quote]

Yes, it should be.