TABLE VII.

Anharmonic corrections to the IR intensities (in km mol⁻¹) of trans-2,3-dideuteriooxirane within a hybrid scheme using the best-estimated (bestCC) harmonic wavenumbers defined in Eq. (4)

Mode	Symmetry	B3LYP/ SNSD	B3LYP/ aug-cc-pVTZ	CAM-B3LYP/ SNSD	B2PLYP/ aug-cc-pVTZ	MP2/ aug-cc-pVTZ	CCSD(T)/ cc-pVTZ	Assignment
1	A	0.70	0.70	0.76	0.67	0.70	– a	CH sym stretch
2	A	−0.47	−0.42	−0.45	−0.37	−0.18	– a	CD sym stretch
3	A	−1.24	−1.07	−1.46	−1.00	−0.90	−0.90	CHD sym scissor
4	A	0.52	0.57	0.40	0.45	0.41	0.12	ring breathing
5	A	0.23	0.23	0.05	0.41	0.66	0.21	CH sym twisting
6	A	−4.60	−4.47	−4.99	−4.63	−4.80	−4.22	CHD wagging
7	A	2.86	2.64	3.79	2.67	2.58	2.56	ring CC stretching
8	A	0.19	0.15	0.03	−0.09	0.20	−0.45	CD sym twisting
9	B	8.95	8.79	7.60	7.73	5.66	4.33	CH asym stretch
10	B	−2.17	−2.31	−2.46	−1.93	−1.22	−2.00	CD asym stretch
11	B	−0.03	−0.03	−0.02	−0.02	0.01	−0.07	CHD asym scissor
12	B	−0.11	−0.13	−0.13	−0.15	−0.13	−0.21	CH asym twisting
13	B	−0.09	−0.12	−0.16	−0.13	−0.08	−0.21	CD asym twisting
14	B	0.91	0.90	0.96	0.67	0.55	0.34	CO asym stretching
15	B	−0.05	−0.06	−0.06	−0.06	−0.07	−0.01	CHD rocking
MAE Fundb		0.6	0.6	0.6	0.4	0.4
∣MAX Fund∣b		4.6	4.5	3.3	3.4	1.3
MAE Allc		0.1	0.1	0.1	0.1	0.1
∣MAX All∣c		4.6	4.5	3.3	3.4	1.3

^aBands involved in Fermi resonances, for which CCSD(T)/cc-pVTZ computations with the CFour code report unreliable anharmonic corrections, were excluded from the analysis.

^bMean absolute error (MAE) and maximum absolute deviations (∣MAX∣), with respect to the hybrid force field with the anharmonic part at the CCSD(T)/cc-pVTZ level, computed for IR intensities of fundamental bands.

^cMean absolute error (MAE) and maximum absolute deviations (∣MAX∣), with respect to the hybrid force field with the anharmonic part at the CCSD(T)/cc-pVTZ level, computed for IR intensities of fundamental bands, overtones and combinational bands.