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# Compare vibrational frequencies for two calculations for C5H7N (1H-Pyrrole, 1-methyl-)

### A = HF/6-31G* B = MP2/6-31G*

scale factors=0.8985, 0.943 0.914 -0.822 -0.104
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   3098 3125 -26.7 0.991   1.108 1.109 -0.001 0.999   1.94 1.29 1.505
2 A A   3091 3117 -25.9 0.992   1.102 1.101 0.001 1.001   16.39 5.03 3.257
3 A A   3078 3106 -28.8 0.991   1.093 1.092 0.000 1.000   9.39 2.84 3.308
4 A A   3067 3098 -31.1 0.990   1.088 1.087 0.001 1.001   3.26 1.05 3.090
5 A A   2974 3039 -65.0 0.979   1.106 1.106 0.000 1.000   22.15 8.44 2.625
6 A A   2949 3016 -67.0 0.978   1.100 1.105 -0.005 0.995   36.23 16.08 2.253
7 A A   2889 2933 -43.9 0.985   1.038 1.033 0.005 1.005   71.81 44.69 1.607
8 A A   1547 1493 54.8 1.037   3.883 2.968 1.308   2.84 32.70 0.087
9 A A   1519 1491 28.3 1.019   2.644 3.465 0.763   59.18 0.88 67.587
10 A A   1492 1485 7.0 1.005   1.083 1.187 0.912   4.23 8.17 0.518
11 A A   1471 1461 10.8 1.007   1.052 1.059 -0.007 0.993   11.56 12.39 0.933
12 A A   1442 1413 29.0 1.021   1.299 1.316 -0.017 0.987   34.43 13.43 2.564
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.