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Compare vibrational frequencies for two calculations for CH2F (fluoromethyl radical)


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

scale factors=0.8985, 0.943 0.134
  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'   2982 3036 -54.5 0.982   1.042 1.041 0.000 1.000   17.09 13.50 1.266
2 A' A'   1452 1457 -4.7 0.997   1.146 1.149 -0.003 0.997   15.27 9.87 1.547
3 A' A'   1140 1137 3.2 1.003   6.220 6.086 1.022   132.05 102.51 1.288
4 A' A'   773 727 45.8 1.063   1.288 1.289 -0.002 0.999   14.45 25.77 0.561
5 A" A"   3108 3181 -73.2 0.977   1.127 1.129 -0.001 0.999   32.20 19.81 1.626
6 A" A"   1150 1144 6.6 1.006   1.218 1.219 -0.000 1.000   12.32 7.23 1.705
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.