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Compare vibrational frequencies for two calculations for C3H7ONO (Propyl nitrite)


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

scale factors=0.8985, 0.943 5.096 0.220 -0.287 0.922
  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'   2945 3021 -75.6 0.975   1.101 1.103 -0.002 0.999   44.71 20.76 2.154
2 A' A'   2905 2946 -40.7 0.986   1.057 1.060 -0.003 0.997   48.63 23.42 2.077
3 A' A'   2895 2931 -35.6 0.988   1.062 1.038 0.024 1.023   12.46 23.53 0.530
4 A' A'   2878 2927 -49.2 0.983   1.038 1.056 -0.018 0.983   27.74 12.51 2.218
5 A' A'   1809 1531 277.7 1.181   14.285 9.189 1.555   242.79 93.80 2.588
6 A' A'   1504 1490 14.9 1.010   1.090 1.123 -0.032 0.971   9.48 20.78 0.456
7 A' A'   1487 1480 7.0 1.005   1.105 1.092 0.014 1.012   3.38 2.44 1.383
8 A' A'   1472 1469 3.0 1.002   1.051 1.058 -0.007 0.994   0.72 2.42 0.298
9 A' A'   1421 1391 30.5 1.022   1.477 1.257 1.175   23.28 2.50 9.322
10 A' A'   1409 1375 34.0 1.025   1.235 1.522 0.812   7.77 27.11 0.287
11 A' A'   1322 1288 34.1 1.026   1.345 1.319 0.027 1.020   14.32 10.62 1.348
12 A' A'   1147 1125 22.6 1.020   3.381 2.459 1.375   16.46 4.67 3.527
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.