TABLE VI.

Anharmonic corrections to the vibrational wavenumbers (in cm⁻¹) of trans-2,3-dideuterooxirane 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	−134.1	−132.1	−136.6	−138.6	−139.9	−143.1	CH sym stretch
2	A	−78.6	−77.8	−82.3	−81.9	−83.9	−84.3	CD sym stretch
3	A	−35.2	−34.8	−36.7	−37.7	−39.9	−39.2	CHD sym scissor
4	A	−24.7	−25.0	−25.4	−27.0	−27.0	−28.2	ring breathing
5	A	−26.3	−26.0	−28.9	−29.3	−29.0	−30.6	CH sym twisting
6	A	−18.8	−18.8	−21.5	−19.6	−19.8	−21.0	CHD wagging
7	A	−17.4	−17.5	−16.5	−19.7	−18.0	−19.6	ring CC stretching
8	A	−12.5	−12.4	−13.4	−14.2	−13.7	−15.6	CD sym twisting
9	B	−135.4	−133.3	−137.6	−139.8	−141.0	−146.8	CH asym stretch
10	B	−77.9	−77.2	−79.4	−81.2	−82.0	−85.5	CD asym stretch
11	B	−28.5	−28.3	−28.6	−30.6	−31.7	−36.0	CHD asym scissor
12	B	−22.2	−22.8	−23.8	−25.4	−23.9	−29.0	CH asym twisting
13	B	−14.2	−14.7	−16.1	−16.0	−15.0	−20.2	CD asym twisting
14	B	−25.3	−24.5	−26.5	−26.3	−25.8	−26.1	CO asym stretching
15	B	−7.1	−7.3	−7.9	−9.0	−8.7	−11.4	CHD rocking
MAE Funda		5.2	5.6	3.8	2.7	2.6
∣MAX∣ Funda		11.4	13.5	9.1	7.0	5.8
MAE Allb		10.2	11.1	7.5	5.3	5.0
∣MAX∣ Allb		28.5	35.5	20.6	14.4	14.6

^aMean 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 fundamental transitions.

^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 fundamental transitions, overtones and combinational bands.