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Compare vibrational frequencies for two calculations for C2H6N2O2 (Dimethylnitroamine)


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

scale factors=0.8985, 0.943 -1.627 0.145 0.190 -0.190
  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   3027 3076 -48.6 0.984   1.106 1.105 0.001 1.001   9.61 2.71 3.548
2 A A   3024 3073 -49.7 0.984   1.103 1.104 -0.000 1.000   5.31 0.88 6.010
3 A A   2987 3028 -40.9 0.986   1.092 1.094 -0.001 0.999   48.16 24.75 1.946
4 A A   2977 3023 -46.1 0.985   1.096 1.096 0.000 1.000   0.01 0.03 0.473
5 A A   2904 2926 -21.8 0.993   1.047 1.044 0.003 1.003   42.42 35.39 1.199
6 A A   2898 2922 -24.3 0.992   1.044 1.043 0.001 1.001   26.03 15.05 1.730
7 A A   1646 1684 -38.6 0.977   11.994 13.621 0.881   543.01 168.37 3.225
8 A A   1499 1485 14.3 1.010   1.208 1.062 1.137   128.39 51.35 2.500
9 A A   1488 1466 22.3 1.015   1.238 1.048 1.181   20.44 0.09 233.638
10 A A   1478 1465 13.4 1.009   1.051 1.090 -0.039 0.964   1.52 12.56 0.121
11 A A   1470 1451 18.5 1.013   1.095 1.055 0.040 1.038   24.15 12.27 1.968
12 A A   1465 1441 24.0 1.017   1.051 1.242 0.847   8.37 31.73 0.264
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.