Basis set recommendation for the SAPT(DFT) method

SAPT
1

I’m interested in comparing the interactions energy between two molecules which will adopt different configurations. The system is basically CNOH plus a few F, Cl, Br.

It seems that my computation resource could afford aug-cc-pVDZ or def2-TZVPD.

I know that for DFT, def2-TZVPD is better than aug-cc-pVDZ. but SAPT(DFT) would also need to do perturbation, so the diffuse functions are quite important.

I wonder what is developers opinion? Thank you.

2

def2-TZVPPD is a fine choice, IMO. Better than aug DZ.
You can also see if jun-cc-pVTZ is affortable, which reduces the standard “aug” set by a lot.
In any case, removing diffuse bfs from the hydrogens is usually a save choice for interaction energies also in the def2-D augmentation.

1 Like
3

Thank you for the advice.