Hi PSI4 developers,
I’m confused while reading the SAPT manual page regarding the GRAC shift.
it says:" For SAPT(DFT), the user will need to manually specify the GRAC shift of both monomers, defined by the difference of ionization potential (IP) and Kohn-Sham HOMO energy." From this the shift is calculated as \del = IP - E_{HOMO} or \del = E_{HOMO} - IP , however, neither of this is the formula the original paper indicates, which is \del = IP + E_{HOMO} and this is in accordance with what Molpro manual says.
I’ve seen an earlier thread mentioning this error in the manual, but the corrections have not been made. It would be much easier for the general users to make full use of PSI4 if this ambiguity in the manual could be fixed. Thanks you!