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

Vibrational frequency scaling factors

Calculated vibrational frequencies ("theory" in table) are calculated at MP4/6-311G**
Scale factor How many Source
Molecules Vibrations
0.970 ± 0.033 17 62 cccbdb
Jump to histogram
Formula Name Mode Symmetry Frequency Count
Theory Experiment ratio molecules vibrations
H2CO Formaldehyde 1 A1 2914 2782 0.955 1 1
    2 A1 1750 1746 0.998 1 2
    3 A1 1545 1500 0.971 1 3
    4 B1 1188 1167 0.983 1 4
    5 B2 2969 2843 0.957 1 5
    6 B2 1273 1249 0.981 1 6
CH4 Methane 1 A1 3042 2917 0.959 2 7
    2 E 1566 1534 0.980 2 8
    3 T2 3168 3019 0.953 2 9
    4 T2 1359 1306 0.961 2 10
C2H4 Ethylene 1 Ag 3160 3026 0.958 3 11
    2 Ag 1662 1623 0.976 3 12
    3 Ag 1367 1342 0.982 3 13
    4 Au 1048 1023 0.976 3 14
    5 B1u 3142 2989 0.951 3 15
    6 B1u 1474 1444 0.979 3 16
    7 B2g 892 940 1.053 3 17
    8 B2u 3253 3105 0.955 3 18
    9 B2u 820 826 1.007 3 19
    10 B3g 3226 3086 0.957 3 20
    11 B3g 1229 1217 0.990 3 21
    12 B3u 954 949 0.996 3 22
C2H2 Acetylene 1 Σg 3522 3374 0.958 4 23
    2 Σg 1954 1974 1.010 4 24
    3 Σu 3431 3289 0.959 4 25
    4 Πg 514 612 1.190 4 26
    5 Πu 754 730 0.968 4 27
C3H6 Cyclopropane 1 A1' 3156 3038 0.962 5 28
    2 A1' 1536 1479 0.963 5 29
    3 A1' 1220 1188 0.974 5 30
    4 A1" 1173 1126 0.960 5 31
    5 A2' 1093 1070 0.979 5 32
    6 A2" 3253 3103 0.954 5 33
    7 A2" 865 854 0.987 5 34
    8 E' 3146 3025 0.961 5 35
    9 E' 1484 1438 0.969 5 36
    10 E' 1085 1029 0.948 5 37
    11 E' 896 866 0.966 5 38
    12 E" 3233 3082 0.953 5 39
    13 E" 1227 1188 0.968 5 40
    14 E" 754 739 0.980 5 41
CO2 Carbon dioxide 1 Σg 1271 1333 1.049 6 42
    2 Σu 2368 2349 0.992 6 43
    3 Πu 635 667 1.050 6 44
CO Carbon monoxide 1 Σ 2010 2170 1.079 7 45
H2 Hydrogen diatomic 1 Σg 4456 4401 0.988 8 46
CH Methylidyne 1 Σ 3156 3145 0.996 9 47
SO2 Sulfur dioxide 1 A1 974 1151 1.182 10 48
    2 A1 472 518 1.097 10 49
    3 B2 1198 1362 1.136 10 50
LiH Lithium Hydride 1 Σ 1425 1405 0.986 11 51
HCl Hydrogen chloride 1 Σ 3047 2991 0.982 12 52
HF Hydrogen fluoride 1 Σ 4238 4138 0.977 13 53
NH3 Ammonia 1 A1 3481 3337 0.959 14 54
    2 A1 1147 950 0.828 14 55
    3 E 3614 3444 0.953 14 56
    4 E 1672 1627 0.973 14 57
N2 Nitrogen diatomic 1 Σg 2184 2359 1.080 15 58
H2O Water 1 A1 3880 3657 0.943 16 59
    2 A1 1680 1595 0.950 16 60
    3 B2 3978 3756 0.944 16 61
F2 Fluorine diatomic 1 Σg 791 917 1.159 17 62

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.

30
25
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