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Vibrational frequency scaling factors


Calculated vibrational frequencies ("theory" in table) are calculated at ROHF/6-31+G**
Scale factor How many Source
Molecules Vibrations
0.856 ± 0.155 39 62 cccbdb
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Formula Name Mode Symmetry Frequency Count
Theory Experiment ratio molecules vibrations
MgH magnesium monohydride 1 Σ 1575 1432 0.909 1 1
CH Methylidyne 1 Σ 3100 2733 0.882 2 2
SiH Silylidyne 1 Σ 2187 1971 0.901 3 3
NH Imidogen 1 Σ 3565 3126 0.877 4 4
SiN Silicon nitride 1 Σ 1306 1138 0.871 5 5
PH phosphorus monohydride 1 Σ 2551 2276 0.892 6 6
CP Carbon monophosphide 1 Σ 1447 1226 0.847 7 7
OH Hydroxyl radical 1 Σ 4072 3570 0.877 8 8
LiO lithium oxide 1 Σ 844 799 0.947 9 9
NaO sodium monoxide 1 Σ 499     10 10
HS Mercapto radical 1 Σ 2878 2599 0.903 11 11
BS boron sulfide 1 Σ 1266 1167 0.922 12 12
SO Sulfur monoxide 1 Σ 1340 1138 0.849 13 13
    1 Σ 1327 1054 0.794 13 14
AlS Aluminum sulfide 1 Σ 679 610 0.898 14 15
S2 Sulfur diatomic 1 Σg 816 720 0.883 15 16
BeF Beryllium monofluoride 1 Σ 1270     16 17
CF Fluoromethylidyne 1 Σ 1380 1286 0.932 17 18
NF nitrogen fluoride 1 Σ 1237 1123 0.908 18 19
MgF Magnesium monofluoride 1 Σ 728     19 20
SiF silicon monofluoride 1 Σ 873 848 0.971 20 21
PF phosphorus monofluoride 1 Σ 875 838 0.958 21 22
BeCl beryllium monochloride 1 Σ 856 847 0.990 22 23
CCl carbon monochloride 1 Σ 876 866 0.988 23 24
ClO Monochlorine monoxide 1 Σ 863 843 0.977 24 25
MgCl magnesium monochloride 1 Σ 455     25 26
SiCl Clorosilylidyne 1 Σ 526 531 1.011 26 27
BH2 boron dihydride 2 A1 1127 954 0.846 27 28
AlH2 aluminum dihydride 1 A1 1962 1770 0.902 28 29
    2 A1 825 760 0.921 28 30
    3 B2 1975 1807 0.915 28 31
PH2 Phosphino radical 1 A1 2553 2310 0.905 29 32
    2 A1 1241 1102 0.888 29 33
HCO Formyl radical 1 A' 3036 2434 0.802 30 34
    2 A' 2139 1868 0.873 30 35
    3 A' 1262 1081 0.857 30 36
HO2 Hydroperoxy radical 1 A' 4087 3436 0.841 31 37
    2 A' 1601 1392 0.869 31 38
    3 A' 1251 1098 0.877 31 39
NF2 Difluoroamino radical 1 A1 1252 1075 0.859 32 40
    2 A1 653 573 0.878 32 41
    3 B2 1168 942 0.807 32 42
OClO Chlorine dioxide 1 A1 1060 946 0.892 33 43
    2 A1 509 448 0.880 33 44
    3 B2 1257 1110 0.883 33 45
ClS2 Sulfur chloride 1 A' 593 662 1.116 34 46
    2 A' 525 450 0.857 34 47
    3 A' 239 196 0.819 34 48
SiH3 Silyl radical 1 A1 2364 2136 0.904 35 49
    2 A1 901 728 0.808 35 50
    3 E 2383 2185 0.917 35 51
    4 E 1018 922 0.906 35 52
CF3 Trifluoromethyl radical 1 A1 1206 1089 0.903 36 53
    2 A1 756 701 0.927 36 54
    3 E 1416 1260 0.890 36 55
    4 E 550 509 0.925 36 56
C3H3 Propargyl radical 1 A1 3638 3322 0.913 37 57
    6 B1 765 687 0.898 37 58
    7 B1 519 490 0.945 37 59

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 30 1 1 1 1 1 1 1 1 1 1 1 1 1 1
40 25 1 1 1 1 1 1 1 1 1 1 1 1 1 1
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