Table 2. Vertical Excitation Energies (ΔE, in eV), Oscillator Strengths (f_osc), and Leading Characters of the Different States of oNBA^33a.

ADC(2)/cc-pVTZ				MS(12,12)-CASPT2(18,14)/cc-pVTZ				bexp.24
state	ΔE	fosc	characterc	state	ΔE	fosc	characterd	ΔE
S1	3.48	0.001	nCOπ*	S1	3.58	0.001	nCOπ*
S2	3.63	0.008	nNO2–π*	S2	3.77	0.004	nNO2–π*	3.7
S3	4.17	0.001	nNO2+π*	S3	4.20	0.001	nNO2+π*
S4	4.66	0.024	ππ* (Lb)	S4	4.54	0.003	ππ* (Lb)	4.4
S5	5.14	0.006	nCOπ* (CT)	S6	6.10	0.001	nCOπ* (CT)
S6	5.42	0.149	ππ* (La)	S5	5.58	0.058	ππ* (La)	5.2
T1	3.14		nCOπ*	T1	3.37		nCOπ*
T2	3.31		nNO2–π*/ππ* (La)	T2	3.49		ππ*(NO2)
T3	3.67		ππ* (NO2)	T3	3.53		nNO2–π*/ππ* (La)
T4	3.87		nNO2+π*/ππ* (La)	T4	3.70		nNO2+π*/ππ* (La)

^aMore details on state characters and weights can be found in Table S4 and Figures S2 and S3 in the SI.

^bExperimental results from Gaussian fits to the absorption spectrum.²⁴

^cSee transition densities in Figure S2 in the SI.

^dSee transition densities in Figure S3 in the SI.