[QE-users] High-entropy oxides

[mkondrin at hppi.troitsk.ru]

Hi Connor, 

Convergence means that changing some input parameter you get variation of 
structure energy is in the margin set according to certain criteria. So, if 
you think that energy upon variation ecutwfc from 70 to 80 changes not much 
then you can consider your calculations converged.

As a rule of thumb ecutwfc equal to 70-75 is enough for normconserving 
pseudopotentials and can be even less (30 40) for ultrasoft/paw ones.

Sincerely yours, 
M. V. Kondrin

On Sep 24 2022, Connor Wilson wrote:

>Hi everyone,
>
> I apologize if what follows is a neophytic question. I'm currently 
> studying the vibrational properties of high-entropy oxides (HEOs). I've 
> managed to relax a 64-atom supercell of HEO such that the force acting on 
> each atom is less than 1E-6 Ry/au. My confusion regards the optimal 
> choice of ecutwfc, kpoints, etc.
>
> I understand I should perform convergence tests with respect to the 
> parameters I'm interested in, and as I intend on studying the phonons, I 
> should think this entails converging the forces, stresses, and lattice 
> parameters.
>
> Therefore: to choose the optimal ecutwfc (say), should I perform vc-relax 
> calculations using ecutwfc=60,70,etc, and chose the value of ecutwfc 
> which gives the best compromise between runtime and force, stress, 
> lattice parameter, etc convergence? Would this be a reasonable way of 
> conducting the convergence testing?
>
>Thank you for your help,
>
>
>Connor Wilson
>MSc candidate in Condensed Matter Physics
>Brock University
>St. Catharines, ON, CAN, L2S 3A1
>