Performance of functionals and basis sets in DFT calculation of organic
compounds redox potentials
The performance of functionals and basis sets is evaluated using density
functional theory with polarized continuum model to calculate redox
potentials of small organic compounds in acetonitrile. Pople basis sets
6-31G, 6-31G*, 6-31G**, 6-31+G*, 6-31+G**, 6-31++G** and functionals at
different levels of the Jacob’s Ladder are studied: PW91, PBE, M06-L,
B3LYP, PBE0, M06-2X, CAM-B3LYP, $\omega$B97X-D3. It is
shown that performance studies should not be done considering oxidation
and reduction reactions together, but analyzing them separately.
Functional M06-2X has a more consistent and uniform response both in
reductions and oxidations and the presence of diffuse functions in the
basis sets is relevant to the accuracy of the predictions. The
computational effort against accuracy is also evaluated.