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Vibrational frequency scaling factors


Calculated vibrational frequencies ("theory" in table) are calculated at MP2=FULL/6-31G(2df,p)
Scale factor How many Source
Molecules Vibrations
0.940 ± 0.024 162 1388 cccbdb
Jump to histogram
Formula Name Mode Symmetry Frequency Count
Theory Experiment ratio molecules vibrations
C2 Carbon diatomic 1 Σg 1895 1827 0.965 1 1
PH phosphorus monohydride 1 Σ 2463 2276 0.924 2 2
    1 Σ 2485 2319 0.933 2 3
SO Sulfur monoxide 1 Σ 1135 1138 1.002 3 4
    1 Σ 1020 1054 1.033 3 5
S2 Sulfur diatomic 1 Σg 725 720 0.994 4 6
C3H2N2 Malononitrile 1 A1 3130 2935 0.938 5 7
    2 A1 2243 2275 1.014 5 8
    3 A1 1475 1395 0.945 5 9
    4 A1 918 890 0.970 5 10
    5 A1 590 582 0.986 5 11
    6 A1 152 167 1.098 5 12
    7 A2 1286 1220 0.948 5 13
    8 A2 399 367 0.919 5 14
    9 B1 3186 2968 0.931 5 15
    10 B1 955 933 0.977 5 16
    11 B1 367 337 0.918 5 17
    12 B2 2248 2275 1.012 5 18
    13 B2 1362 1318 0.968 5 19
    14 B2 1010 982 0.972 5 20
    15 B2 392 366 0.934 5 21

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.

40 20 1 1 1 1 1 1 1 1 1 1 1 1 1 1
40 15 1 1 1 1 1 1 1 1 1 1 1 1 1 1
40 10 1 1 1 1 1 1 1 1 1 1 1 1 1 1
40 5 1 1 1 1 1 1 1 1 1 1 1 1 1 1
40 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1
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