Table 5. Absorption Wavelengths λ_Max (nm), Excitation Energies, E_ex (eV), and Oscillator Strengths (f) Calculated by TD/DFT-B3LYP/6-31+G(d,p) Method for all of the trans-Azo Compounds and FL From the Initial Optimized Geometry at B3LYP/6-31+G(d,p).

compound	electronic transition	λmax	f	Ex	MOa	MOb	symc	wave functionsd,e
trans-DZ	S0 → S1	387.78	0.0000	3.1972	8 → 9	0.70891	BG	H → L (100%)
	S0 → S2	184.08	0.0000	6.7354	8 → 10	0.70579	AG	H → L + 1 (99%)
	S0 → S3	178.97	0.0386	6.9277	8 → 11	0.70527	BU	H → L + 2 (99%)
trans-DFDZ	S0 → S1	227.47	0.0000	5.4505	16 → 17	0.70544	BG	H → L (99%)
	S0 → S2	189.32	0.0111	6.5490	15 → 17	0.29661	BU	H – 1 → L (17%)
					16 → 18	0.63732		H → L + 1 (81%)
	S0 → S3	179.59	0.0000	6.9033	15 → 18	0.70238	BG	H – 1 → L + 1 (98%)
trans-AzoFL	S0 → S1	489.35	0.0000	2.5336	93 → 95	0.69879	B	H – 1 → L (97%)
	S0 → S2	423.53	1.5595	2.9274	94 → 95	0.70581	B	H → L (99%)
	S0 → S3	344.48	0.0000	3.5992	92 → 95	0.68177	A	H – 2 → L (92%)
					94 → 96	–0.13547		H → L + 1 (3%)
FL	S0 → S1	276.39	0.1648	4.4858	42 → 45	0.22186	B2	H – 2 → L (9%)
					42 → 46	0.11652		H – 2→L + 1 (2%)
					44 → 45	0.48597		H → L (47%)
					44 → 46	–0.43727		H → L + 1 (38%)
	S0 → S2	265.77	0.2862	4.6650	42 → 45	–0.15521	B2	H – 2 → L (4%)
					44 → 45	0.48553		H → L (47%)
					44 → 46	0.48096		H → L + 1 (46%)
	S0 → S3	256.82	0.0072	4.8277	43 → 45	0.55822	A1	H – 1 → L (62%)
					44 → 47	–0.40501		H → L + 2 (32%)

^aMolecular orbitals involved in the transition.

^bMolecular orbital coefficients.

^csym, orbital symmetry-singlet.

^dThe wave functions based on the eigenvectors predicted by TD-DFT. H and L are used to denote the HOMO and LUMO.

^ePercentage of contribution obtained by (100 × c × c × 2), where c is the co-efficient.