PBE exchange functional used for the ADMM correction

[Torstein Fjermestad]

CP2K version 2025.2

Dear all, 

For the ADMM correction, there seems to be two versions of the PBE functional. Two of the values of the keyword “EXCH_CORRECTION_FUNC” are “DEFAULT” (“Use PBE-based corrections according to the chosen interaction operator”) and “PBEX” (“Use PBEX functional for exchange correction”).

What is the difference between these two PBE exchange functionals?

Thanks for your help.

Best regards,

Torstein

[Frederick Stein]

Dear Torstein,

With "PBEX", CP2K uses PBE as exchange correction independently of the interaction operator. With "DEFAULT", CP2K uses an exchange correction depending on the interaction operator and based on the PBE functional, i.e. different corrections for shortranged-Coulomb operator or the traditional Coulomb-operator.

Best,

Frederick