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

Compare vibrational frequencies for two calculations for C6H12 (Pentane, 3-methylene-)

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   3052 3103 -51.1 0.984   1.116 1.117 -0.000 1.000   27.95 16.83 11.11 1.660
2 A A   2987 3019 -32.2 0.989   1.063 1.065 -0.003 0.997   16.15 19.49 -3.33 0.829
3 A A   2946 3018 -72.5 0.976   1.104 1.098 0.006 1.005   71.02 15.90 55.12 4.467
4 A A   2940 3016 -75.7 0.975   1.103 1.103 0.000 1.000   59.81 30.44 29.36 1.964
5 A A   2936 3011 -75.7 0.975   1.102 1.103 -0.001 0.999   99.14 46.63 52.52 2.126
6 A A   2935 3011 -76.1 0.975   1.103 1.103 -0.000 1.000   14.13 5.86 8.27 2.412
7 A A   2913 2964 -51.2 0.983   1.100 1.103 -0.003 0.997   18.61 19.23 -0.63 0.967
8 A A   2911 2964 -52.5 0.982   1.098 1.103 -0.005 0.995   6.58 15.10 -8.53 0.436
9 A A   2884 2929 -45.4 0.984   1.050 1.036 0.014 1.014   29.21 28.98 0.23 1.008
10 A A   2880 2929 -48.6 0.983   1.039 1.036 0.003 1.003   67.85 17.64 50.21 3.846
11 A A   2877 2918 -40.7 0.986   1.063 1.061 0.002 1.002   30.29 0.00 30.29 18934.310
12 A A   2874 2916 -42.1 0.986   1.053 1.061 -0.008 0.992   3.03 32.29 -29.27 0.094
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.