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. 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 IX.

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

Mode B3LYPa CAMa B2PLYPb/
 MP2b best cheapc/
 Exp.d Best IRe Assignment
B3LYP B2PLYP B3LYP CAM B2PLYP MP2
1 3019 3057 3058 3055 3098 3058 3060 3056 3055 3051 24.51 CH2 asym stretch
2 2974 3009 3005 3006 3041 3002 3004 3003 3000 3001 40.62 CH stretch
3 2963 2988 2997 2995 3021 2992 2984 2990 2981 2995 18.66 CH3 asym stretch
4 2949 2994 2981 2980 3028 2978 2992 2978 2986 2974 22.75 CH3 asym stretch
5 2913 2957 2945 2940 2952 2933 2935 2928 2924 25.55 CH2 sym stretch
6 2935 2965 2970 2967 2979 2960 2962 2956 2952 2942 13.73 CH3 sym stretch
7 1505 1505 1504 1502 1516 1507 1507 1504 1504 1514 5.11 CH2 scisor
8 1450 1460 1472 1470 1472 1468 1468 1466 1462 1459 6.02 CH3 asym def
9 1437 1447 1459 1453 1456 1453 1453 1449 1445 1447 3.40 CH3 asym def
10 1399 1420 1413 1410 1409 1409 1409 1406 1403 1411 14.55 CHx bending
11 1366 1378 1383 1379 1371 1378 1379 1374 1370 1371 2.67 CH3 umbrella
12 1264 1283 1272 1269 1268 1262 1263 1260 1258 1271 5.15 ring breathing
13 1158 1172 1171 1170 1168 1169 1169 1168 1167 1170 0.88 CH2 rocking
14 1133 1150 1147 1145 1143 1143 1142 1141 1140 1147 3.45 CH bending
15 1125 1144 1136 1133 1128 1131 1131 1129 1128 1133 1.52 CH2 wagging
16 1102 1117 1111 1108 1105 1106 1107 1103 1102 1108 5.14 CH2 twist
17 1013 1026 1027 1024 1024 1024 1024 1021 1020 1027 7.81 CH2,CH3 rocking
18 948 975 952 951 955 952 950 950 949 954 11.50 ring deformation
19 888 901 898 895 895 894 895 891 891 894 2.71 CH2, CH3 rocking
20 821 852 826 825 838 832 831 831 830 834 44.18 ring CC stretching
21 751 784 748 746 756 752 752 750 750 756 7.76 CO asym stretching
22 410 417 410 409 408 407 407 406 407 409 3.97 CH3 bend
23 364 371 368 367 368 369 370 368 369 375 4.06 CH3 bend
24 193 195 208 200 206 208 200 198 191 200 0.35 CH3 torsion
MAEf 12.0 9.6 6.2 5.1 11.7 4.8 5.7 5.2 6.1
∣MAX∣f 32.4 28.2 28.1 24.6 53.3 17.8 20.2 14.2 13.9
MAEg 11.1 11.2 6.1 4.1 12.0 2.7 3.5 2.6
∣MAX∣g 36.8 34.1 16.9 11.7 49.6 9.1 14.1 9.3
a

Computed with the SNSD basis set.

b

Computed with the aug-cc-pVTZ basis set.

c

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

d

Experimental results. The 2900-3100 cm−1 wavenumbers range: high-resolution jet-cooled IR spectrum from Ref.106. The 200-1600 cm−1 wavenumbers range: low-temperature matrix data from Refs.3,27.

e

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

f

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

g

Mean absolute error (MAE) and maximum absolute deviations (∣MAX∣) with respect to the best theoretical estimates (best cheap/B2PLYP).