. Author manuscript; available in PMC: 2015 Oct 21.

Published in final edited form as: J Chem Phys. 2014 Jul 21;141(3):034107. doi: 10.1063/1.4887357

TABLE VIII.

Anharmonic fundamental vibrational wavenumbers (in cm⁻¹) of trans-2,3-dideuteriooxirane computed with hybrid schemes and the best-estimated anharmonic IR intensities (in km mol ⁻¹).

Mode	Symmetry	B3LYP^a	CAM-B3LYP^a	B2PLYP^b/		MP2^b	best cheap^c/			bestCC^d/					Exp.^e	Best IR^f	Assignment
				B3LYP	B2PLYP		B3LYP	B2PLYP	CC^g	B3LYP	CAM	B2PLYP	MP2	CC^f
1	A	2995	3027	3034	3029	3068	3036	3031	3027	3036	3033	3031	3030	3027	3015	6.32	CH sym stretch
2	A	2235	2261	2259	2256	2285	2255	2252	2250	2257	2253	2254	2252	2251	2254	6.30	CD sym stretch
3	A	1391	1415	1399	1397	1397	1391	1389	1387	1392	1390	1389	1387	1388	1397	4.93	CHD sym scissor
4	A	1233	1254	1237	1235	1238	1229	1227	1226	1231	1231	1229	1229	1228	1235	7.23	ring breathing
5	A	1104	1120	1116	1113	1111	1111	1108	1107	1112	1109	1109	1109	1108	1112	0.30	CH sym twisting
6	A	955	975	958	957	955	953	953	951	958	955	957	957	955	961	26.18	CHD wagging
7	A	877	895	882	879	886	879	877	877	882	883	879	881	879	885	25.65	Ring deformation
8	A	747	756	755	753	757	755	754	752	756	755	755	755	753	754	21.29	CD sym twisting
9	B	2999	3031	3039	3035	3073	3041	3036	3029	3039	3037	3035	3034	3028	3028	14.39	CH asym stretch
10	B	2220	2244	2245	2241	2266	2244	2241	2237	2245	2243	2242	2241	2237	2240	17.01	CD asym stretch
11	B	1331	1340	1344	1342	1341	1332	1329	1324	1331	1331	1329	1328	1323	1339	0.07	CHD asym scissor
12	B	1099	1113	1113	1109	1107	1111	1107	1104	1111	1109	1108	1109	1104	1106	1.81	CH asym twisting
13	B	911	924	918	916	913	913	912	907	914	912	913	914	908	914	2.73	CD asym twisting
14	B	813	858	806	805	815	807	806	807	814	813	813	814	814	817	7.51	Ring deformation
15	B	655	661	661	660	660	658	656	654	658	657	656	656	654	673	0.30	CHD rocking
MAE^h		10.9	11.2	6.2	4.6	12.6	7.0	7.1	7.8	6.0	5.9	5.8	5.8	6.4
∣MAX∣^h		28.6	40.6	18.6	14.1	53.4	20.7	17.0	19.4	20.9	18.4	16.9	16.6	19.3
MAEⁱ		8.9	14.4	8.2	5.8	14.3	5.0	3.1	1.6	5.2	3.8	2.7	2.6
∣MAX∣ⁱ		32.0	43.9	21.0	18.9	45.3	12.7	8.2	7.1	11.4	9.1	7.0	5.8

Computed with the SNSD basis set.

Computed with the aug-cc-pVTZ basis set.

Best-estimated (best) harmonic wavenumbers obtained by means of the “cheap” scheme according to Eq. (5).

Best-estimated (bestCC) harmonic wavenumbers obtained at the CCSD(T) level according to Eq. (4).

Experimental gas-phase data from Ref.⁹

Best-estimated anharmonic IR intensities computed at the bestCC/B2PLYP level.

Anharmonic corrections computed at the CCSD(T)/cc-pVTZ level.

Mean absolute error (MAE) and maximum absolute deviations (∣MAX∣) with respect to experiment.

ⁱ

Mean absolute error (MAE) and maximum absolute deviations (∣MAX∣) with respect to the best theoretical estimates (bestCC//CCSD(T)/VTZ).