[CP2K-user] [CP2K:22073] r2SCAN CUTOFF convergence

[Jürg Hutter]

Hi

maybe you can try to see if the energy difference between two structures converges?

BTW you can also use GAPW with your original GPW setting (basis & PP).

best regards
JH

________________________________________
From: 'Max H' via cp2k <cp2k at googlegroups.com>
Sent: Friday, January 30, 2026 12:59 PM
To: cp2k
Subject: [CP2K:22071] r2SCAN CUTOFF convergence

Dear all,

I am trying to implement the r2SCAN functional for my calculations and struggle to converge the values for the CUTOFF and REL_CUTOFF. As some have observed earlier, it is difficult to get the accuracy below 10^-3 Hartree and I encounter the same challenge for my system (Cu, O, C and H).
I tried the following steps to resolve this issue, albeit without success:

  1.  Raise CUTOFF systematically up to 3000 at REL_CUTOFF 100 (same at 200).
  2.  Apply smoothing in the XC_GRID section, e.g. XC_DERIV SPLINE3_SMOOTH and XC_SMOOTH_RHO NN10 (and NN50).
  3.  Use the GPAW method instead of GPW (as some noted that CUTOFF convergence is easier).

I have been using the DZVP-MOLOPT-SCAN-GTH basis sets and the GTH-SCAN pseudopotentials for the tests with GPW and the 6-31G* basis set for GPAW.
The input files are attached (although I left out the exact structures, as the problem should be quite general).

I would appreciate your suggestions to solve this issue or point it out if I made an obvious mistake.

All the best,
Max


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