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

Compare vibrational frequencies for two calculations for C5H8 (Cyclopentene)

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'   3045 3076 -30.5 0.990   1.105 1.104 0.001 1.001   31.84 20.60 11.24 1.546
2 A' A'   2938 3000 -62.0 0.979   1.106 1.107 -0.001 0.999   73.53 35.05 38.48 2.098
3 A' A'   2910 2966 -56.1 0.981   1.077 1.096 -0.019 0.983   72.47 30.76 41.71 2.356
4 A' A'   2890 2942 -51.9 0.982   1.082 1.065 0.017 1.016   12.61 18.81 -6.20 0.671
5 A' A'   2864 2908 -43.9 0.985   1.070 1.066 0.004 1.004   36.65 22.05 14.61 1.663
6 A' A'   1664 1596 68.1 1.043   5.972 5.664 0.307 1.054   1.32 0.70 0.62 1.894
7 A' A'   1494 1480 13.9 1.009   1.109 1.110 -0.002 0.998   0.16 0.83 -0.68 0.187
8 A' A'   1466 1457 8.9 1.006   1.087 1.090 -0.003 0.997   0.68 2.01 -1.32 0.341
9 A' A'   1329 1294 34.7 1.027   1.655 1.738 -0.083 0.952   0.04 0.67 -0.63 0.058
10 A' A'   1216 1199 17.1 1.014   1.215 1.232 -0.017 0.987   1.62 1.38 0.24 1.177
11 A' A'   1108 1092 16.3 1.015   1.095 1.094 0.000 1.000   0.06 0.16 -0.11 0.345
12 A' A'   1063 1042 20.6 1.020   1.702 1.708 -0.006 0.997   10.01 5.21 4.80 1.921
13 A' A'   935 952 -16.7 0.982   2.462 2.489 -0.027 0.989   1.45 1.10 0.36 1.326
14 A' A'   867 891 -23.4 0.974   3.138 2.860 0.278 1.097   0.56 0.50 0.05 1.106
15 A' A'   802 812 -10.7 0.987   1.552 1.678 -0.126 0.925   2.45 0.25 2.20 9.975
16 A' A'   710 683 27.2 1.040   1.371 1.334 0.036 1.027   33.31 32.14 1.17 1.036
17 A' A'   596 571 25.2 1.044   1.688 1.601 0.087 1.055   7.55 10.54 -2.99 0.716
18 A' A'   135 173 -37.7 0.782   1.602 1.598 0.004 1.002   0.11 0.16 -0.05 0.690
19 A" A"   3021 3054 -32.7 0.989   1.086 1.086 0.000 1.000   12.75 5.06 7.69 2.521
20 A" A"   2901 2965 -64.0 0.978   1.096 1.099 -0.003 0.997   41.10 18.80 22.30 2.186
21 A" A"   2865 2910 -45.0 0.985   1.069 1.065 0.004 1.003   78.95 44.32 34.62 1.781
22 A" A"   1476 1464 11.8 1.008   1.100 1.091 0.008 1.008   0.04 0.95 -0.91 0.039
23 A" A"   1365 1336 29.0 1.022   1.627 1.682 -0.055 0.967   1.71 1.64 0.07 1.042
24 A" A"   1311 1293 18.1 1.014   1.356 1.287 0.070 1.054   1.46 1.02 0.44 1.435
25 A" A"   1297 1265 32.0 1.025   1.329 1.335 -0.006 0.996   2.16 1.32 0.84 1.634
26 A" A"   1217 1182 34.9 1.030   1.312 1.488 -0.177 0.881   0.00 0.00 0.00 2.143
27 A" A"   1137 1114 23.5 1.021   1.221 1.172 0.049 1.042   1.76 1.73 0.03 1.017
28 A" A"   1006 1017 -10.2 0.990   1.826 1.727 0.099 1.057   1.64 1.02 0.61 1.601
29 A" A"   981 904 76.9 1.085   1.232 1.637 -0.405 0.753   0.04 2.88 -2.85 0.012
30 A" A"   890 892 -2.2 0.998   1.526 1.354 0.172 1.127   2.48 3.88 -1.39 0.641
31 A" A"   868 873 -5.6 0.994   1.774 1.457 0.317 1.218   4.71 0.87 3.83 5.393
32 A" A"   752 739 13.2 1.018   5.442 4.875 0.567 1.116   0.34 0.13 0.21 2.563
33 A" A"   379 371 8.1 1.022   2.028 2.147 -0.119 0.945   0.01 0.10 -0.09 0.115
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.