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

Compare vibrational frequencies for two calculations for HCNH (HCNH)

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'   3219 3249 -29.6 0.991   1.075 1.100 -0.026 0.977   2.51 18.09 -15.58 0.139
2 A' A'   2919 2884 35.8 1.012   1.088 1.262 -0.174 0.862   33.03 324.78 -291.75 0.102
3 A' A'   1497 2339 -841.5 0.640   6.433 3.734 2.699 1.723   0.67 389.44 -388.76 0.002
4 A' A'   1137 986 151.3 1.154   1.474 1.255 0.219 1.174   116.70 89.73 26.97 1.301
5 A' A'   910 699 211.1 1.302   1.045 1.172 -0.127 0.892   45.48 332.89 -287.41 0.137
6 A" A"   955 895 60.0 1.067   1.285 1.335 -0.050 0.963   8.56 12.06 -3.49 0.710
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.