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Compare vibrational frequencies for two calculations for H2OCH3OH (water methanol 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   3739 3656 82.9 1.023   1.079 1.076 0.003 1.003   123.40 88.62 1.392
2 A A   3697 3562 134.8 1.038   1.067 1.066 0.001 1.001   60.90 39.32 1.549
3 A A   3619 3480 138.4 1.040   1.050 1.052 -0.002 0.998   199.87 221.28 0.903
4 A A   2986 3051 -65.4 0.979   1.102 1.104 -0.003 0.998   36.36 20.80 1.748
5 A A   2931 3006 -75.5 0.975   1.107 1.108 -0.001 0.999   74.55 34.45 2.164
6 A A   2880 2926 -46.5 0.984   1.035 1.033 0.002 1.002   55.24 37.01 1.493
7 A A   1665 1667 -2.3 0.999   1.078 1.077 0.001 1.001   96.43 71.08 1.357
8 A A   1492 1483 9.4 1.006   1.048 1.047 0.001 1.001   2.93 4.19 0.699
9 A A   1482 1476 6.2 1.004   1.049 1.051 -0.002 0.998   2.12 3.82 0.555
10 A A   1470 1446 23.8 1.016   1.151 1.147 0.005 1.004   11.21 4.09 2.741
11 A A   1352 1331 20.7 1.016   1.299 1.272 0.027 1.021   46.66 31.94 1.461
12 A A   1160 1137 22.8 1.020   1.265 1.255 0.010 1.008   3.09 0.29 10.655
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.