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[Chao Cao <cao@qtp.ufl.edu>]

ecut defines your real space grid size, and it's irrelevant if you 
change the volume; however, the # of k-points might need change if you 
change the volume, but unless you change it a lot... I really don't see 
the necessity.

Chao Cao

waigen zhang wrote:
> Dear all,
> I am not sure if this problem asked  by somebody else or ...
> As far as I know, ecut and kpoint convergence test is needed before 
> any physical calculation. How about if we keep changing the pressure 
> (volume)? Say if pressure=0 GPa. ecut=20,ngkpt=4X4X4 is enough. How 
> about when pressure=100 GPa (say volume is 50% of zere pressure 
> volume)? Should we
> double check the ecut and ngkpt before any calculation?
> If we need to check the convergence when volume changes(beyond the 
> ecutsm effect),is there any good way to do that?
> Regards,
> WG.ZHANG


--
Chao Cao

Quantum Theory Project and Department of Physics
University of Florida, Gainesville, FL 32611
U.S.A.