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III.G.7. (XIII.B.3.) (XIII.D.5.)

Compare vibrational frequencies for two calculations for C5H8 (Cyclobutane, methylene-)

A = HF/6-31G*

B = MP2FC/6-31G*

  symmetry   frequency (cm-1)   reduced mass (amu)   IR Intensity (km mol-1)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 A' A'   2984 3022 -38.3 0.987   1.062 1.060 0.002 1.002   12.66 5.36 7.30 2.361
2 A' A'   2959 3017 -58.8 0.981   1.109 1.110 -0.000 1.000   75.02 35.44 39.57 2.117
3 A' A'   2932 2989 -57.0 0.981   1.102 1.108 -0.006 0.995   23.83 12.69 11.15 1.879
4 A' A'   2912 2955 -42.6 0.986   1.066 1.060 0.006 1.006   49.34 35.03 14.31 1.408
5 A' A'   2892 2932 -40.4 0.986   1.063 1.061 0.002 1.002   14.94 8.38 6.55 1.781
6 A' A'   1721 1674 47.6 1.028   6.363 6.664 -0.301 0.955   18.87 9.30 9.57 2.030
7 A' A'   1485 1474 11.0 1.007   1.131 1.126 0.006 1.005   0.30 0.02 0.28 15.688
8 A' A'   1455 1450 5.6 1.004   1.094 1.089 0.005 1.005   1.15 2.46 -1.31 0.469
9 A' A'   1418 1399 19.4 1.014   1.165 1.156 0.009 1.007   0.64 0.68 -0.03 0.951
10 A' A'   1263 1224 39.6 1.032   1.477 1.492 -0.015 0.990   3.82 0.17 3.65 22.247
11 A' A'   1204 1181 23.6 1.020   1.282 1.333 -0.052 0.961   0.18 0.00 0.18 69.346
12 A' A'   1086 1057 28.6 1.027   2.006 1.897 0.109 1.058   0.19 0.27 -0.09 0.689
13 A' A'   932 949 -16.5 0.983   2.219 3.268 -1.049 0.679   16.26 0.36 15.90 45.064
14 A' A'   929 870 59.1 1.068   1.669 2.061 -0.392 0.810   32.79 0.09 32.70 362.701
15 A' A'   859 836 23.4 1.028   2.321 1.321 1.000 1.757   0.37 44.11 -43.74 0.008
16 A' A'   722 729 -7.0 0.990   1.446 1.573 -0.126 0.920   0.80 2.13 -1.32 0.378
17 A' A'   644 638 5.9 1.009   2.691 2.640 0.051 1.019   1.81 1.33 0.49 1.367
18 A' A'   374 360 14.1 1.039   2.089 2.024 0.066 1.032   5.23 4.59 0.64 1.139
19 A' A'   88 113 -25.1 0.779   1.871 2.021 -0.149 0.926   0.02 0.13 -0.12 0.117
20 A" A"   3051 3107 -56.0 0.982   1.117 1.117 -0.000 1.000   19.42 9.82 9.60 1.978
21 A" A"   2936 2992 -56.6 0.981   1.104 1.106 -0.002 0.998   20.78 14.84 5.94 1.400
22 A" A"   2889 2929 -40.3 0.986   1.062 1.060 0.002 1.002   60.84 34.74 26.10 1.751
23 A" A"   1449 1439 10.7 1.007   1.104 1.097 0.007 1.006   1.03 2.48 -1.45 0.414
24 A" A"   1281 1246 35.1 1.028   1.694 1.928 -0.234 0.879   0.29 0.04 0.25 6.572
25 A" A"   1237 1209 27.4 1.023   1.276 1.220 0.056 1.046   0.02 0.23 -0.20 0.095
26 A" A"   1207 1174 32.9 1.028   1.466 1.532 -0.067 0.957   0.71 1.05 -0.35 0.670
27 A" A"   1181 1150 31.4 1.027   1.737 1.649 0.088 1.053   1.61 2.10 -0.48 0.769
28 A" A"   1026 1010 16.7 1.017   1.080 1.086 -0.006 0.995   0.06 0.16 -0.09 0.402
29 A" A"   899 908 -8.5 0.991   2.486 2.434 0.052 1.021   1.14 1.32 -0.18 0.862
30 A" A"   887 884 3.8 1.004   1.727 1.652 0.075 1.046   1.33 0.40 0.93 3.304
31 A" A"   795 792 3.2 1.004   1.142 1.153 -0.011 0.991   0.09 0.22 -0.13 0.394
32 A" A"   630 632 -1.7 0.997   1.042 1.040 0.002 1.002   0.09 0.16 -0.07 0.576
33 A" A"   343 335 8.2 1.025   2.189 2.163 0.026 1.012   0.18 0.03 0.15 5.636
scaled by     0.8985 0.943

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.