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Compare vibrational frequencies for two calculations for CH3OH- (Methyl alcohol anion)


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

scale factors=0.8985, 0.943 0.121
  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'   2552 2566 -13.3 0.995   1.025 1.026 -0.002 0.999   528.65 579.91 0.912
2 A' A'   2461 2527 -65.9 0.974   1.091 1.093 -0.002 0.998   534.65 443.78 1.205
3 A' A'   1486 1485 1.1 1.001   1.168 1.158 0.010 1.008   244.52 231.03 1.058
4 A' A'   1470 1458 12.6 1.009   1.072 1.081 -0.010 0.991   47.61 76.78 0.620
5 A' A'   1170 1153 17.4 1.015   1.328 1.332 -0.003 0.998   5.28 2.72 1.939
6 A' A'   1139 1133 5.8 1.005   6.862 6.741 1.018   257.74 248.16 1.039
7 A' A'   439 624 -184.9 0.704   1.073 1.059 0.014 1.013   356.34 107.07 3.328
8 A' A'   291 332 -40.6 0.878   1.159 1.160 -0.001 1.000   6.07 9.92 0.612
9 A" A"   2480 2510 -30.6 0.988   1.093 1.094 -0.001 0.999   624.27 530.12 1.178
10 A" A"   1463 1444 18.5 1.013   1.070 1.073 -0.002 0.998   45.22 38.89 1.163
11 A" A"   1174 1163 11.0 1.009   1.307 1.302 0.005 1.004   4.52 0.28 15.903
12 A" A"   97 71 26.7 1.378   1.055 1.050 0.004 1.004   2.22 4.70 0.473
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.