[CP2K-user] [CP2K:22345] Help tuning HSE exact-exchange fraction for AlN band gap in CP2K

[Asif Billah]

Hello CP2K community,

I am calculating the bulk AlN band gap using CP2K 2024.1 with HSE, ADMM, a 
72-atom 3x3x2 wurtzite supercell, and Gamma point sampling. My target band 
gap is approximately 6.1 eV.

Using standard diagonalization, Broyden mixing, ADMM_PURIFICATION_METHOD 
NONE, and alpha=0.15, I obtained a converged gap of:
Band gap = 5.267211 eV 

However, when I used alpha=0.20, the SCF initially approached about 5.7 eV 
but later diverged catastrophically. A retry with DIRECT_P_MIXING and a 
level shift produced a NaN in the first SCF step.

Could you please advise: What is the recommended stable procedure or 
strategy so that the calculated bandgap reaches 6.1 eV using HSE 
calculations with ADMM? 

Any guidance would be greatly appreciated.

Thank you.

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/cp2k/4d47782f-5994-47fa-9366-63bda159a137n%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20260728/e0acac8a/attachment.htm>