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Compare vibrational frequencies for two calculations for C5H5NO (3-Pyridinol)


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

scale factors=0.8985, 0.943 0.397 -0.344 -7.808 1.665 -1.026
  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'   3693 3533 160.3 1.045   1.067 1.066 0.001 1.001   89.26 64.21 1.390
2 A' A'   3057 3072 -15.5 0.995   1.099 1.098 0.000 1.000   10.95 4.01 2.729
3 A' A'   3044 3060 -16.0 0.995   1.094 1.093 0.001 1.001   24.17 12.05 2.007
4 A' A'   3029 3044 -15.0 0.995   1.089 1.089 -0.000 1.000   7.32 7.04 1.040
5 A' A'   2998 3002 -4.0 0.999   1.091 1.091 0.000 1.000   39.58 25.56 1.548
6 A' A'   1626 1576 50.1 1.032   6.150 5.753 1.069   18.68 18.36 1.018
7 A' A'   1618 1562 55.3 1.035   5.410 5.754 0.940   19.01 24.70 0.770
8 A' A'   1502 1457 45.1 1.031   2.380 2.325 0.055 1.024   26.84 24.45 1.098
9 A' A'   1449 1412 36.3 1.026   2.516 2.418 0.098 1.041   145.11 110.09 1.318
10 A' A'   1348 1355 -6.8 0.995   1.221 9.030 0.135   23.87 1.70 14.052
11 A' A'   1276 1318 -42.7 0.968   2.890 1.225 2.359   83.68 26.65 3.140
12 A' A'   1215 1255 -39.8 0.968   1.436 2.462 0.583   148.71 59.67 2.492
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.