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

Compare vibrational frequencies for two calculations for C2H6N2O2 (Dimethylnitroamine)

A = HF/6-31G*

B = MP2/6-31G*

scale factors=0.8985, 0.943
  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   3027 3076 -48.6 0.984   1.106 1.105 0.001 1.001   9.61 2.71 6.90 3.550
2 A A   3024 3073 -49.8 0.984   1.103 1.104 -0.000 1.000   5.31 0.88 4.43 6.031
3 A A   2987 3028 -41.0 0.986   1.092 1.094 -0.001 0.999   48.16 24.74 23.42 1.946
4 A A   2977 3023 -46.1 0.985   1.096 1.096 0.000 1.000   0.01 0.03 -0.01 0.473
5 A A   2904 2926 -21.8 0.993   1.047 1.044 0.003 1.003   42.42 35.38 7.04 1.199
6 A A   2898 2923 -24.3 0.992   1.044 1.043 0.001 1.001   26.03 15.03 10.99 1.731
7 A A   1646 1684 -38.5 0.977   11.994 13.621 -1.627 0.881   543.01 168.40 374.60 3.224
8 A A   1499 1485 14.3 1.010   1.208 1.063 0.145 1.137   128.39 51.45 76.94 2.495
9 A A   1488 1466 22.3 1.015   1.238 1.048 0.190 1.181   20.44 0.09 20.36 234.711
10 A A   1478 1465 13.4 1.009   1.051 1.090 -0.040 0.964   1.52 12.58 -11.06 0.121
11 A A   1470 1451 18.5 1.013   1.095 1.055 0.040 1.038   24.15 12.27 11.87 1.967
12 A A   1465 1441 24.0 1.017   1.051 1.242 -0.191 0.847   8.37 31.81 -23.44 0.263
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.