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Compare vibrational frequencies for two calculations for N(CH3)2CONH2 (Urea, N,N-dimethyl-)


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

scale factors=0.8985, 0.943 0.154
  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   3541 3491 50.5 1.014   1.101 1.098 0.003 1.003   38.91 27.59 1.410
2 A A   3440 3381 58.2 1.017   1.049 1.048 0.000 1.000   37.74 26.70 1.413
3 A A   3029 3065 -36.6 0.988   1.097 1.099 -0.002 0.998   4.50 0.10 46.082
4 A A   2977 3035 -57.2 0.981   1.099 1.103 -0.004 0.996   29.26 6.60 4.431
5 A A   2932 2983 -51.0 0.983   1.097 1.095 0.002 1.002   44.71 8.14 5.491
6 A A   2924 2976 -51.7 0.983   1.106 1.104 0.002 1.001   56.21 49.79 1.129
7 A A   2880 2913 -33.2 0.989   1.042 1.037 0.005 1.005   37.52 56.59 0.663
8 A A   2871 2896 -24.4 0.992   1.045 1.045 0.000 1.000   78.65 51.19 1.537
9 A A   1751 1714 36.3 1.021   6.837 6.683 1.023   520.67 359.78 1.447
10 A A   1625 1587 38.2 1.024   1.231 1.208 0.024 1.020   168.26 143.44 1.173
11 A A   1506 1505 0.9 1.001   1.200 1.251 -0.051 0.959   84.64 49.71 1.703
12 A A   1493 1483 10.1 1.007   1.054 1.052 0.002 1.002   2.13 15.61 0.136
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.