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Vibrational frequency scaling factors


Calculated vibrational frequencies ("theory" in table) are calculated at ROHF/6-31G**
Scale factor How many Source
Molecules Vibrations
0.855 ± 0.155 37 60 cccbdb
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Formula Name Mode Symmetry Frequency Count
Theory Experiment ratio molecules vibrations
MgH magnesium monohydride 1 Σ 1577 1432 0.908 1 1
CH Methylidyne 1 Σ 3030 2733 0.902 2 2
SiH Silylidyne 1 Σ 2166 1971 0.910 3 3
NH Imidogen 1 Σ 3551 3126 0.880 4 4
SiN Silicon nitride 1 Σ 1319 1138 0.863 5 5
PH phosphorus monohydride 1 Σ 2527 2276 0.901 6 6
CP Carbon monophosphide 1 Σ 1453 1226 0.844 7 7
OH Hydroxyl radical 1 Σ 4069 3570 0.877 8 8
LiO lithium oxide 1 Σ 888 799 0.900 9 9
NaO sodium monoxide 1 Σ 525     10 10
HS Mercapto radical 1 Σ 2878 2599 0.903 11 11
BS boron sulfide 1 Σ 1269 1167 0.920 12 12
AlS Aluminum sulfide 1 Σ 681 610 0.896 13 13
S2 Sulfur diatomic 1 Σg 819 720 0.880 14 14
BeF Beryllium monofluoride 1 Σ 1318     15 15
CF Fluoromethylidyne 1 Σ 1410 1286 0.912 16 16
MgF Magnesium monofluoride 1 Σ 779     17 17
SiF silicon monofluoride 1 Σ 919 848 0.922 18 18
PF phosphorus monofluoride 1 Σ 912 838 0.919 19 19
BeCl beryllium monochloride 1 Σ 856 847 0.990 20 20
CCl carbon monochloride 1 Σ 872 866 0.993 21 21
ClO Monochlorine monoxide 1 Σ 869 843 0.970 22 22
MgCl magnesium monochloride 1 Σ 459     23 23
SiCl Clorosilylidyne 1 Σ 532 531 0.999 24 24
BH2 boron dihydride 2 A1 1143 954 0.834 25 25
AlH2 aluminum dihydride 1 A1 1960 1770 0.903 26 26
    2 A1 823 760 0.924 26 27
    3 B2 1974 1807 0.915 26 28
PH2 Phosphino radical 1 A1 2554 2310 0.905 27 29
    2 A1 1243 1102 0.886 27 30
BeOH beryllium monohydroxide 2 A' 1312 1246 0.950 28 31
HCO Formyl radical 1 A' 2977 2434 0.818 29 32
    2 A' 2154 1868 0.867 29 33
    3 A' 1264 1081 0.855 29 34
HO2 Hydroperoxy radical 1 A' 4085 3436 0.841 30 35
    2 A' 1603 1392 0.868 30 36
    3 A' 1252 1098 0.877 30 37
NF2 Difluoroamino radical 1 A1 1270 1075 0.846 31 38
    2 A1 653 573 0.877 31 39
    3 B2 1193 942 0.790 31 40
OClO Chlorine dioxide 1 A1 1070 946 0.883 32 41
    2 A1 508 448 0.882 32 42
    3 B2 1275 1110 0.870 32 43
ClS2 Sulfur chloride 1 A' 598 662 1.106 33 44
    2 A' 528 450 0.852 33 45
    3 A' 241 196 0.812 33 46
SiH3 Silyl radical 1 A1 2340 2136 0.913 34 47
    2 A1 895 728 0.813 34 48
    3 E 2359 2185 0.926 34 49
    4 E 1018 922 0.905 34 50
CF3 Trifluoromethyl radical 1 A1 1220 1089 0.892 35 51
    2 A1 759 701 0.924 35 52
    3 E 1442 1260 0.874 35 53
    4 E 550 509 0.924 35 54
C3H3 Propargyl radical 1 A1 3644 3322 0.912 36 55
    6 B1 761 687 0.903 36 56
    7 B1 495 490 0.990 36 57

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