Computational estimates of the low-lying excited electronic states of berberine in acetonitrile using the B3LYP functional and various basis sets. Values are presented in eV and in nm to facilitate comparison to the spectra.

Basis set	E(T1) − E(S0)/eV [nm]	E(S1) − E(S0)/eV [nm]	E(S2) − E(S0)/eVa [nm]
6-31G(d)	2.189 [566]	2.725 [455]	3.424 [362], 3.453 [359]
6-311G(d)	2.203 [563]	2.726 [455]	3.416 [363], 3.447 [360]
cc-pVDZ	2.161 [574]	2.675 [463]	3.379 [367], 3.400 [365]
cc-pVTZ	2.198 [564]	2.722 [456]	3.414 [363], 3.449 [360]
Experiment (λmax)		2.883 [430]	3.553 [349]

^aThe calculations indicate two near-degenerate states.