[QE-users] Query regarding ecutfock

[Arini Kar]

Dear Lorenzo,

Your suggestion was helpful. The forces on the pristine unit cell did 
not change after reducing ecutfock to 2*ecutwfc. Thanks a lot.

Regards
Arini

On 2023-04-12 13:26, Lorenzo Bastonero wrote:

> Dear Arini,
> 
> You should do some test first in the pristine unit cell structure 
> before going forward to the supercell calculations.
> 
> In principle, you could lower down even more that cutoff (and the 
> qpoint for the fock operator as well). Usually a good threshold is 
> ~10^-5 Ry/bohr on every atomic force component.
> 
> Note: this threshold is different from the one of the relax. So you 
> should check that when changing your variables (ecutfock in this case) 
> all your forces don't change within this threshold.
> 
> HTH,
> Lorenzo
> 
> Inviato da iPhone
> 
>> Il giorno 11 apr 2023, alle ore 20:45, Arini Kar via users 
>> <users at lists.quantum-espresso.org> ha scritto:
> 
>> Dear users,
>> 
>> I am trying to run phonon calculations using phonopy. I am using norm 
>> conserving pseudopotential. Can I use ecutfock = 2*ecutwfc instead of 
>> the default value in the scf calculations? Would it affect the 
>> accuracy of force calculations?
>> 
>> Thanking you.
>> 
>> Regards
>> 
>> Arini Kar
>> 
>> PhD student
>> 
>> Indian Institute of Technology Bombay, India
>> 
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