National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 17bSeptember 2015
NIST Standard Reference Database 101
IIntroduction
IIExperimental data
IIICalculated data
IVData comparisons
VCost comparisons
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XIIGeometries
XIII Vibrations
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XVEntropy data
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XVIIIon data
XVIIIBad calculations
XIXIndex of properties
XXH-bond dimers
XXIOddities

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

Compare vibrational frequencies for two calculations for CH3CN+ (Acetonitrile cation)

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   25849 2936 22913.0 8.804   1.376 1.133 0.243 1.214   0.00 51.20 -51.20 0.000
2 ?a A   2940 2911 28.3 1.010   1.106 1.087 0.019 1.017   46.57 145.61 -99.05 0.320
3 ?a A   2842 2844 -1.1 1.000   1.029 5.174 -4.146 0.199   106.21 691.90 -585.69 0.153
4 ?a A   2467 2762 -294.6 0.893   1.013 1.119 -0.106 0.905   426.06 163.29 262.78 2.609
5 ?a A   1997 1362 634.9 1.466   12.300 1.164 11.137 10.572   81.27 24.76 56.51 3.282
6 ?a A   1391 1261 129.8 1.103   1.110 1.099 0.011 1.010   22.74 144.44 -121.70 0.157
7 ?a A   1320 1198 121.1 1.101   1.098 1.139 -0.041 0.964   61.55 26.82 34.73 2.295
8 ?a A   1197 956 241.4 1.252   1.112 3.505 -2.394 0.317   4.15 18.30 -14.15 0.227
9 ?a A   1011 794 216.6 1.273   1.500 1.602 -0.102 0.936   13.28 89.56 -76.29 0.148
10 ?a A   797 525 272.2 1.519   5.268 3.583 1.685 1.470   9.78 106.20 -96.42 0.092
11 ?a A   368 280 88.2 1.315   3.567 3.844 -0.277 0.928   2.15 11.48 -9.33 0.187
12 ?a A   368 165 202.6 2.226   4.610 1.337 3.274 3.450   43.95 105.51 -61.55 0.417
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.