Table 1. Vertical excitation energies (in eV) of uracil at CASSCF and CASPT2 level of theory with different active spaces. State characters are also indicated and oscillator strengths are given in parentheses.

State	Experiments	CASPT2				CASSCF
		SA4/SA3	SA7	SA7	SA5/SA4	SA4/SA3	SA7	SA7
		(14,10)	(14,10)	(12,9)	(10,8)/(14,10) b	(14,10) a	(14,10)	(12,9)
S1	4.38 c	nπ* 4.93 (0.00)	nπ* 4.91	nπ* 4.85	nπ* 4.90	nπ* 5.18	nπ* 5.13	nπ* 4.83
S2	5.1 d	ππ* 5.18 (0.20)	ππ* 5.09	ππ* 5.32	ππ* 5.23	ππ* 6.82	ππ* 7.04	ππ* 7.07
S3	6.0 d	ππ* 6.18 (0.07)	nπ* 6.41	ππ* 6.02	ππ* 6.15	ππ* 7.29	nπ* 7.07	ππ* 7.33
T1	—	ππ* 3.80	ππ* 3.90	ππ* 3.90	—	ππ* 3.98	ππ* 4.00	ππ* 3.93
T2	—	nπ* 4.71	nπ* 4.84	nπ* 4.71	—	nπ* 4.87	nπ* 4.95	nπ* 4.65
T3	—	ππ* 5.33	ππ* 5.54	ππ* 5.47	—	ππ* 5.76	ππ* 5.86	ππ* 5.70

^a Climent et al. ²⁹

^b For ππ*: SA5(A′)-CASPT2(10,8)/6-31G*, for nπ*: SA4(A′′)-CASPT2(14,10)/6-31G* from Schreiber et al. ¹²⁵

^c Masaaki Fujii and Ito. ¹²⁸

^d Clark et al. ¹²⁴