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

Compare vibrational frequencies for two calculations for HCONH2CN2H4 (formamide aminomethanimine dimer)

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   3537 3518 18.7 1.005   1.095 1.089 0.005 1.005   107.74 98.99 8.75 1.088
2 A A   3530 3502 27.6 1.008   1.091 1.087 0.004 1.004   106.49 91.09 15.41 1.169
3 A A   3391 3348 42.9 1.013   1.077 1.077 0.000 1.000   2.19 4.62 -2.43 0.474
4 A A   3359 3261 97.9 1.030   1.059 1.064 -0.005 0.995   393.21 631.21 -238.00 0.623
5 A A   3265 3113 151.5 1.049   1.066 1.072 -0.005 0.995   424.33 594.75 -170.41 0.713
6 A A   2945 2955 -10.2 0.997   1.091 1.091 0.001 1.001   78.82 78.93 -0.11 0.999
7 A A   2889 2880 8.8 1.003   1.089 1.088 0.000 1.000   149.62 164.84 -15.22 0.908
8 A A   1766 1723 42.6 1.025   5.067 4.295 0.773 1.180   745.82 490.76 255.06 1.520
9 A A   1706 1684 22.0 1.013   2.357 2.226 0.131 1.059   172.64 94.22 78.42 1.832
10 A A   1647 1608 38.8 1.024   1.359 1.427 -0.067 0.953   24.34 6.59 17.75 3.695
11 A A   1632 1597 34.3 1.021   1.384 1.422 -0.038 0.973   23.94 10.53 13.41 2.274
12 A A   1423 1381 42.0 1.030   1.805 1.967 -0.162 0.918   55.51 30.68 24.83 1.809
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.