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Compare vibrational frequencies for two calculations for H2CN (H2CN)


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

scale factors=0.8985, 0.943 -7.169 1.035
  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   2908 2920 -12.7 0.996   1.047 1.058 -0.011 0.989   0.22 0.00 47.956
2 A1 A1   1473 1959 -486.5 0.752   1.770 8.939 0.198   12.22 13.28 0.920
3 A1 A1   1292 1376 -83.9 0.939   2.099 1.065 1.972   0.02 17.04 0.001
4 B1 B1   928 1106 -178.2 0.839   1.345 1.362 -0.017 0.988   31.84 32.23 0.988
5 B2 B2   2983 2984 -1.0 1.000   1.116 1.113 0.003 1.003   16.39 11.27 1.454
6 B2 B2   964 929 34.9 1.038   1.326 1.353 -0.027 0.980   15.05 7.11 2.117
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.