[QE-users] Convergence with interstitials

[Tejas Ramakrishnan]

Thanks Mostafa,

I tried both options, but continue to have convergence issues. I repeated the check with up to 8 x 8 x 8 k-points to some sense (but not to the threshold) of convergence (0.0x Ry at about 100 iterations), but larger than that the memory requirements overshoot > 256 GB).
CG diagonalization also doesn’t help.

Ends in same large scf error divergence quickly. I have attached one of the runs’ “in and out” here.

I am trying a finer k-point mesh 12x12x12 and a bit larger smearing with 3x3x3 cell now to see if as discussed in some other threads to avoid issues with occupation states.
I have been perusing literature and see some where even 2 x 2 x 2 cells work for some (I do note that not many are for metallic systems), but there are studies on Fe, NI and W where even 2x2x2 or 3x3x3 super cell seem to work.

Not sure what I am missing. Any thoughts?

Regards,
Tejas

From: users <users-bounces at lists.quantum-espresso.org> On Behalf Of Mostafa Youssef via users
Sent: Saturday, January 9, 2021 03:48 PM
To: users at lists.quantum-espresso.org
Subject: [QE-users] Convergence with interstitials

Dear Tejas,

I see two issues:

1) Your supercell size is too small. This corresponds to a high concentration of N. I would go for 4x4x4 conventional cells of W. That is 128 atoms.

2) A magnetic moment on N is needed since the odd number of electrons is because of N.


Regards,
Mostafa
AUC

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