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Compare vibrational frequencies for two calculations for HNNO+ (Nitrous oxide, N-protonated)


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

scale factors=0.8985, 0.943 -0.468 -0.482 12.271 -6.928 3.490
  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'   3249 3259 -10.1 0.997   1.115 1.119 -0.004 0.996   971.07 806.14 1.205
2 A' A'   2374 2356 17.8 1.008   9.028 9.495 0.951   822.32 109.27 7.526
3 A' A'   1468 1309 159.0 1.122   9.575 10.057 0.952   46.78 1.38 34.008
4 A' A'   653 733 -80.0 0.891   13.465 1.193 11.284   40.05 272.18 0.147
5 A' A'   440 535 -95.2 0.822   1.145 8.074 0.142   488.35 2.53 192.848
6 A" A"   637 591 45.6 1.077   6.762 3.272 2.067   0.49 21.09 0.023
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.