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III.B.3.b. (XIII.C.2.)

Vibrational frequency scaling factors

Calculated vibrational frequencies ("theory" in table) are calculated at B2PLYP=FULL/6-31G*
Scale factor How many Source
Molecules Vibrations
0.948 ± 0.018 140 2510 cccbdb
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Formula Name Mode Symmetry Frequency Count
Theory Experiment ratio molecules vibrations
CH3OH Methyl alcohol 1 A' 3786 3681 0.972 1 1
    2 A' 3178 3000 0.944 1 2
    3 A' 3040 2844 0.936 1 3
    4 A' 1564 1477 0.945 1 4
    5 A' 1530 1455 0.951 1 5
    6 A' 1414 1345 0.951 1 6
    7 A' 1107 1060 0.958 1 7
    8 A' 1079 1033 0.958 1 8
    9 A" 3090 2960 0.958 1 9
    10 A" 1548 1477 0.954 1 10
    11 A" 1197 1165 0.973 1 11
    12 A" 348 200 0.574 1 12

How do we calculate the scaling factor?


Histogram of vibrational frequency ratios

Ratios greater than 1.35 are in the 1.35 bin. Ratios less than 0.7 are in the 0.7 bin.

20
15
10
5
0
0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35
Ratio of experimental frequency to calculated frequency