Dear all,
I have been trying to do the SAPT calculation for the metal complexes using ESP.
I have used the basis set AUG-CC-PVDZ
but it shows the error like: Fatal Error: RHF: RHF reference is only for singlets.
Has anyone had a similar problem, and if so, how did you solve it?
The error message means that “by default, Psi4 assumes Hartree-Fock is for spin-singlet (closed shell) systems, but this system isn’t closed shell.” If the system is not closed shell, set reference uhf to change the default. If the system is closed shell, your molecule specification is incorrect - you probably forgot a hydrogen.
For SAPT, all subsystems need to be closed-shell unless the default value of reference is overridden.