The , , and operators proposed by Andersson [Theor. Chim. Acta 91, 31 (1995)] as well as a further operator may be used. makes CASPT2 calculations size extensive for cases in which a molecule dissociates to high-spin open-shell (RHF) atoms.
The index n of the operator to be used is specified on the RS2, RS2C, or RS3 card:
where option can be G1, G2, G3, or G4. This option can be followed or preceded by other valid options.