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Compare vibrational frequencies for two calculations for C5H10O (2-Pentanone)


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

scale factors=0.8985, 0.943 1.819 0.217
  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'   2984 3048 -64.2 0.979   1.103 1.104 -0.002 0.999   15.90 6.60 2.409
2 A' A'   2934 3011 -76.8 0.974   1.100 1.103 -0.002 0.998   58.73 27.93 2.103
3 A' A'   2901 2947 -46.4 0.984   1.063 1.062 0.002 1.002   16.51 14.52 1.136
4 A' A'   2883 2929 -46.1 0.984   1.040 1.037 0.003 1.003   13.23 3.80 3.481
5 A' A'   2872 2924 -51.9 0.982   1.038 1.036 0.002 1.002   39.45 22.13 1.783
6 A' A'   2860 2900 -40.0 0.986   1.060 1.061 -0.001 0.999   12.15 10.21 1.191
7 A' A'   1810 1681 128.7 1.077   11.136 9.317 1.195   197.99 74.52 2.657
8 A' A'   1485 1480 4.2 1.003   1.086 1.074 0.012 1.011   3.73 5.22 0.715
9 A' A'   1469 1464 4.3 1.003   1.057 1.062 -0.005 0.995   1.87 2.71 0.690
10 A' A'   1450 1445 5.1 1.004   1.070 1.069 0.001 1.001   15.94 17.92 0.890
11 A' A'   1443 1434 9.4 1.007   1.076 1.083 -0.007 0.993   0.89 3.47 0.258
12 A' A'   1412 1390 22.5 1.016   1.498 1.281 1.169   18.16 3.98 4.569
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.