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

Compare vibrational frequencies for two calculations for C3H7ONO (Propyl nitrite)

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'   2945 3021 -75.5 0.975   1.101 1.103 -0.002 0.999   44.71 20.75 23.95 2.154
2 A' A'   2905 2946 -40.5 0.986   1.057 1.060 -0.003 0.997   48.63 23.34 25.29 2.084
3 A' A'   2895 2931 -35.5 0.988   1.062 1.038 0.024 1.024   12.46 22.82 -10.36 0.546
4 A' A'   2878 2927 -48.7 0.983   1.038 1.056 -0.018 0.983   27.74 13.37 14.37 2.074
5 A' A'   1809 1530 278.9 1.182   14.285 9.002 5.284 1.587   242.79 92.84 149.95 2.615
6 A' A'   1504 1490 14.9 1.010   1.090 1.125 -0.035 0.969   9.48 21.29 -11.81 0.445
7 A' A'   1487 1480 6.9 1.005   1.105 1.092 0.013 1.012   3.38 2.47 0.91 1.369
8 A' A'   1472 1469 3.0 1.002   1.051 1.058 -0.007 0.994   0.72 2.43 -1.71 0.297
9 A' A'   1421 1391 30.5 1.022   1.477 1.258 0.219 1.175   23.28 2.49 20.79 9.354
10 A' A'   1409 1375 33.9 1.025   1.235 1.522 -0.287 0.812   7.77 27.26 -19.49 0.285
11 A' A'   1322 1288 34.0 1.026   1.345 1.319 0.027 1.020   14.32 10.63 3.69 1.347
12 A' A'   1147 1125 22.6 1.020   3.381 2.460 0.921 1.374   16.46 4.61 11.85 3.570
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.