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Compare vibrational frequencies for two calculations for NH3- (Ammonia anion)


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 A1 A1   2466 2481 -15.0 0.994   1.053 1.051 0.002 1.002   11.94 10.48 1.140
2 A1 A1   1006 1030 -24.5 0.976   1.148 1.150 -0.002 0.998   72.16 78.66 0.917
3 E E   1822 2125 -303.1 0.857   1.121 1.105 0.016 1.015   6101.59 2168.70 2.813
4 E E   1822 2125 -303.1 0.857   1.121 1.105 0.016 1.015   6101.59 2168.70 2.813
5 E E   1319 1307 12.1 1.009   1.024 1.035 -0.011 0.990   239.30 4.93 48.535
6 E E   1319 1307 12.1 1.009   1.024 1.035 -0.011 0.990   239.30 4.93 48.535
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.