Posted by Coen de Graaf on May 12, 2011 at 14:46:41:
In Reply to: Using of AFRE keyword posted by Jose Luis Pascual on May 10, 2011 at 17:21:44:
Hola Jose-Luis,
As far as I understand it, there is not really much to say about the AFRE keyword. You select the atoms that you consider to belong to the active site and MOLCAS selects the orbitals to be included in the CASPT2 calculation based on the coefficients in the molecular orbitals of the basis functions of these atoms. If this is higher than the threshold you give in the input it is included and otherwise the orbital is either frozen or deleted. The output explicitly tells you how many orbitals are included in the CASPT2 after the selection by the criteria of the AFRE keyword. Something like this:
Additional orbitals will be frozen or deleted
Selected atoms: FE N1 N2 N3
Frozen orbitals before selection: 27 27
Inactive orbitals before selection: 64 69
Secondary orbitals before selection: 238 245
Deleted orbitals before selection: 0 0
Frozen orbitals after selection 81 81
Inactive orbitals after selection 10 15
Seondary orbitals after selection: 238 245
Deleted orbitals after selection: 0 0
As far as I know there is no article where the AFRE option is specifically discussed.
All the best,
Coen