[CP2K-user] SCAN convergence problems for charged systems

[Chris Ahart]

Dear CP2K users,

I am attempting to use the SCAN functional from libXC 4.2.1 with CP2K 6, 
performing some basic benchmark calculations from the G12IP dataset. While 
SCAN converges well for neutrals systems, I am unable to get convergence 
for a charged system.

I attach an example of the CH4 system (input and output for both neutral 
and charged), where the neutral state converges within 20 steps while the 
charged state immediately diverges. I have observed the same behaviour with 
many other systems. I have also tried using LDA pseudopotentials as well as 
the SCAN optimised pseudopotentials from github.com/juerghutter/GTH, in 
addition to all electron calculations. I have confirmed that the same input 
file converges with HF, and with PBE from both the CP2K implementation and 
from libXC.

I have also found that the charged system converges when only the 
correlation part of the SCAN functional is included, suggesting that the 
problem may be related to the exchange part of the SCAN functional.

Any help with this problem would be greatly appreciated.

Regards,
Chris
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