[CP2K-user] SCF convergence problem with large basis sets
tom.bra... at ugent.be
Mon Jul 5 11:44:49 UTC 2021
Dear CP2K users/developers,
I was performing some benchmarks related to the basis set size (with simply
PBE-D3). In particular, I was checking the energy difference between
benzene adsorbed in the H-SSZ-13 zeolite and its protonated counterpart.
While I can see a steady improvement going from DZVP -> TZVP -> TZV2P
(without any issue in the calculation) I encountered large problems in the
SCF convergence when using even larger basis sets, like the QZV2(or 3)P and
the augmented basis sets. At this point, I was only able to converge a
couple calculations with the QZV3P using the CG optimizer (normally I use
the DIIS) and the FULL_KINETIC preconditioner (I normally use the
FULL_SINGLE_INVERSE), which according to the manual should be more robust.
I also tried the diagonalization method instead of the OT one but also in
that case the scf was not converging.
The problem is that even with the two converged calculations the energy
difference between the two species I'm studying results to be ~3000kJ/mol
vs the expected ~100kJ/mol, thus it looks like the two scf have converged
to different minima.
Does anybody know how to robustly converge the scf with large basis sets?
In attachment the input and output of the supposedly converged calculations.
Thank you in advance,
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