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XIII.F.1. (III.B.7.a.) (XVIII.B.1.)

Bad Vibrational Frequency Predictions

Unscaled vibrational frequencies calculated at MP2/6-31G* are generally lower than frequencies calculated at HF/6-31G*. This page lists vibrational modes for which that is not true, which may be a warning of a vibrational mode for which the harmonic assumption is poor, or the calculation at HF or MP2 is a poor description of the molecule. The vibrational numbering may not align for all calculations. This will result in some molecules listed here for which the vibrational frequency calculations are reasonable. Click on an entry for a comparison of all the vibrational frequencies for that molecule at HF/6-31G* and MP2/6-31G*.
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
HCl- hydrogen chloride anion 1 Σ 70 91 0.7681 2.37 11.89 0.1994 1.04 1.04 1.0000
CuH Copper monohydride 1 Σ 1783 2302 0.7744 420.27 431.66 0.9736 1.02 1.02 1.0000
HBr- hydrogen bromide anion 1 Σ 150 193 0.7756 10.47 31.62 0.3311 1.02 1.02 1.0000
Li2+ lithium diatomic cation 1 Σg 260 488 0.5327 0.00 0.00   7.02 7.02 1.0000
LiBe Lithium Beryllium 1 Σ 238 313 0.7603 66.55 173.84 0.3828 7.77 7.77 1.0000
Be2- Beryllium dimer anion 1 Σg 357 505 0.7077 0.00 0.00   9.01 9.01 1.0000
Be2 Beryllium diatomic 1 Σg 36 49 0.7404 0.00 0.00   9.01 9.01 1.0000
B2 Boron diatomic 1 Σg 904 1123 0.8050 0.00 0.00   11.01 11.01 1.0000
BC+ boron monocarbide cation 1 Σ 448 1647 0.2720 0.28 640.85 0.0004 11.46 11.46 1.0000
CN Cyano radical 1 Σ 1982 2863 0.6925 13.45 20.37 0.6600 12.85 12.85 1.0000
BN- boron nitride anion 1 Σ 1616 2217 0.7287 83.27 198.04 0.4205 12.15 12.15 1.0000
BN+ boron nitride cation 1 Σ 1535 2576 0.5957 46.36 2704.23 0.0171 12.15 12.15 1.0000
BeN- Beryllium mononitride anion 1 Σ 1379 3103 0.4445 271.51     10.47 10.47 1.0000
CO+ carbon monoxide cation 1 Σ 2392 2887 0.8287 4.48 629.15 0.0071 13.44 13.44 1.0000
NO Nitric oxide 1 Σ 2221 3913 0.5678 69.51 2712.69 0.0256 14.87 14.87 1.0000
FO Oxygen monofluoride 1 Σ 1176 2489 0.4723 37.37 699.86 0.0534 17.24 17.24 1.0000
FO+ fluorine monoxide cation 1 Σ 1340 1745 0.7676 89.82 172.40 0.5210 17.24 17.24 1.0000
Ne2 Neon dimer 1 Σg 78 106 0.7362 0.00 0.00   19.99 19.99 1.0000
NaF+ sodium fluoride cation 1 Σ 159 180 0.8824 20.93 22.97 0.9112 20.62 20.62 1.0000
NaBe Sodium Beryllium 1 Σ 124 154 0.8068 5.57 41.65 0.1338 10.87 10.87 1.0000
NaO- sodium oxide anion 1 Σ 384 797 0.4809 109.93 312.57 0.3517 18.28 18.28 1.0000
NaO+ sodium oxide cation 1 Σ 58 190 0.3046 21.81 16.96 1.2857 18.28 18.28 1.0000
Na2+ sodium dimer cation 1 Σg 121 246 0.4917 0.00 0.06 0.0000 22.99 22.99 1.0000
MgO magnesium oxide 1 Σ 768 1071 0.7170 115.76 1148.54 0.1008 18.45 18.45 1.0000
LiMg Lithium magnesium 1 Σ 95 109 0.8730 1.28 18.08 0.0707 8.35 8.35 1.0000
NaMg Sodium Magnesium 1 Σ 4 18 0.2042 0.00 0.07 0.0060 23.47 23.47 1.0000
MgF+ magnesium fluoride cation 1 Σ 110 844 0.1298 54.93 66.78 0.8226 20.92 20.92 1.0000
Mg2- magnesium dimer anion 1 Σg 79 103 0.7719 0.00 0.00   23.99 23.99 1.0000
AlO+ aluminum monoxide cation 1 Σ 805 1352 0.5956 116.48 590.27 0.1973 18.85 18.85 1.0000
AlN- aluminum mononitride anion 1 Σ 610 1074 0.5675 40.41 157.16 0.2571 16.76 16.76 1.0000
Al2 Aluminum diatomic 1 Σg 316 362 0.8741 0.00 0.00   26.98 26.98 1.0000
SiC- silicon monocarbide anion 1 Σ 766 1072 0.7145 8.10 20.15 0.4019 14.48 14.48 1.0000
SiN Silicon nitride 1 Σ 915 1476 0.6196 41.88 359.03 0.1166 16.80 16.80 1.0000
SiN+ silicon mononitride cation 1 Σ 601 1241 0.4845 30.69 603.60 0.0508 16.80 16.80 1.0000
CP Carbon monophosphide 1 Σ 1011 1209 0.8362 2.36 28.77 0.0821 14.48 14.48 1.0000
PO Phosphorus monoxide 1 Σ 1404 4103 0.3422 68.38 91842.43 0.0007 19.15 19.15 1.0000
PN- phosphorus nitride anion 1 Σ 877 1158 0.7573 52.97 32.88 1.6109 16.88 16.88 1.0000
PN+ phosphorus nitride cation 1 Σ 758 1513 0.5010 66.96 72.41 0.9247 16.88 16.88 1.0000
CS+ carbon monosulfide cation 1 Σ 1248 1454 0.8582 3.21 51.64 0.0622 14.47 14.47 1.0000
NS- nitrogen sulfide anion 1 Σ 863 969 0.8902 50.85 52.62 0.9664 16.90 16.90 1.0000
NS Mononitrogen monosulfide 1 Σ 894 1486 0.6016 23.57 84.12 0.2802 16.90 16.90 1.0000
AlS Aluminum sulfide 1 Σ 615 707 0.8699 8.12 54.12 0.1501 29.06 29.06 1.0000
AlS+ aluminum monosulfide cation 1 Σ 567 730 0.7767 0.02 43.81 0.0005 29.06 29.06 1.0000
PS phosphorus sulfide 1 Σ 547 1252 0.4374 0.05 870.74 0.0001 31.46 31.46 1.0000
SiS+ silicon monosulfide cation 1 Σ 690 924 0.7464 0.23 163.08 0.0014 29.71 29.71 1.0000
SO- sulfur monoxide anion 1 Σ 736 1156 0.6364 39.62 6.68 5.9312 19.19 19.19 1.0000
CCl- carbon monochloride anion 1 Σ 272 444 0.6138 127.71 94.39 1.3530 14.42 14.42 1.0000
LiCl+ lithium chloride cation 1 Σ 286 320 0.8929 140.43 134.97 1.0405 8.10 8.10 1.0000
NaCl+ sodium chloride cation 1 Σ 137 159 0.8608 33.09 32.09 1.0310 26.60 26.60 1.0000
NCl- nitrogen monochloride anion 1 Σ 375 581 0.6457 104.50 27.63 3.7818 16.90 16.90 1.0000
NCl+ nitrogen monochloride cation 1 Σ 748 1822 0.4102 2.24 1886.11 0.0012 16.90 16.90 1.0000
AlCl- aluminum monochloride anion 1 Σ 308 350 0.8803 115.35 94.52 1.2203 29.96 29.96 1.0000
BeCl- beryllium monochloride anion 1 Σ 447 530 0.8432 124.77 90.88 1.3729 10.63 10.63 1.0000
MgCl- magnesium monochloride anion 1 Σ 285 322 0.8853 74.21 53.39 1.3900 27.50 27.50 1.0000
ClO- chlorine monoxide anion 1 Σ 519 709 0.7316 48.32 0.67 72.0386 19.28 19.28 1.0000
ClO+ chlorine monoxide cation 1 Σ 1031 1391 0.7410 160.79 0.01 12863.3100 19.28 19.28 1.0000
BCl- boron monochloride anion 1 Σ 269 433 0.6225 171.90 143.38 1.1988 13.17 13.17 1.0000
Ca2 Calcium dimer 1 Σg 2 21 0.1155 0.00 0.00   39.96 39.96 1.0000
CuCl Copper monochloride 1 Σ 382 474 0.8051 42.05 54.95 0.7652 41.57 41.57 1.0000
Cu2 Copper dimer 1 Σg 304 405 0.7491 0.00 0.00   62.93 62.93 1.0000
CuF Copper monofluoride 1 Σ 665 836 0.7955 88.95 118.93 0.7479 22.67 22.67 1.0000
ZnO zinc monoxide 1 Σ 673 1001 0.6726 49.30 391.72 0.1259 18.82 18.82 1.0000
GaO Gallium monoxide 1 Σ 632 707 0.8935 51.18 1.10 46.3689 18.70 18.70 1.0000
GaN Gallium mononitride 1 Σ 541 696 0.7782 11.82 224.76 0.0526 16.18 16.18 1.0000
SeO- selenium monoxide anion 1 Σ 588 887 0.6631 0.17 91.90 0.0018 18.46 18.46 1.0000
CSe+ Carbon monoselenide cation 1 Σ 1019 1459 0.6981 3.17 183.79 0.0172 13.50 13.50 1.0000
BrCl+ bromine chloride cation 1 Σ 492 605 0.8130 19.00 40.13 0.4734 42.18 42.18 1.0000
BrF- bromine fluoride anion 1 Σ 93 495 0.1879 13.10 138.08 0.0949 22.28 22.28 1.0000
NBr nitrogen monobromide 1 Σ 594 729 0.8150 38.93 56.98 0.6833 15.98 15.98 1.0000
BrO- Bromine monoxide anion 1 Σ 493 644 0.7649 9.78 15.88 0.6159 18.48 18.48 1.0000
BrO Bromine monoxide 1 Σ 638 787 0.8107 2.55 4.40 0.5793 18.48 18.48 1.0000
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
H2S- Hydrogen sulfide anion 3 A' 75 240 0.3129 16.75 17.52 0.9558 1.06 1.04 1.0175
C2H+ Ethynyl cation 3 Π 551 787 0.7005 60.92 44.60 1.3661 1.32 1.33 0.9941
C2H+ Ethynyl cation 2 Σ 1813 2124 0.8534 44.53 3.93 11.3308 6.49 5.32 1.2218
HCN- Hydrogen cyanide anion 1 A' 2003 2459 0.8145 463.84 615.61 0.7535 1.40 6.64 0.2103
HCN- Hydrogen cyanide anion 3 A' 885 1033 0.8561 80.47 158.17 0.5087 1.29 1.24 1.0332
HCN+ hydrogen cyanide cation 2 Σ 2084 2958 0.7045 47.81 336.76 0.1420 5.53 1.25 4.4325
HCN+ hydrogen cyanide cation 1 Σ 3420 3971 0.8612 261.48 1.27 205.9242 1.17 4.27 0.2740
NNH Dinitrogen monohydride 2 A' 2053 2829 0.7257 23.93 69.60 0.3438 11.95 1.72 6.9275
HCO- formyl anion 3 A' 1368 1775 0.7707 1966.82 391.70 5.0212 1.66 1.96 0.8485
HNO+ Nitrosyl hydride cation 1 A' 3153 5301 0.5947 275.34 15096.72 0.0182 1.07 12.44 0.0864
HNO+ Nitrosyl hydride cation 2 A' 2037 2962 0.6876 34.70 395.51 0.0877 10.04 1.06 9.4460
FHF- FHF- 2 Σu 1363 1608 0.8475 3073.70 2681.71 1.1462 1.03 1.03 1.0000
MgOH magnesium hydroxide 3 A' 83 258 0.3224 199.37 157.91 1.2626 1.17 1.21 0.9620
HNS- HNS- 3 A' 774 871 0.8892 17.00 38.05 0.4468 13.34 14.64 0.9109
HCS- Thioformyl anion 3 A' 960 2710 0.3542 62.18 449.77 0.1383 9.65 1.09 8.8714
HCS Thioformyl radical 2 A' 1032 1606 0.6427 0.90 295.82 0.0030 7.07 8.70 0.8130
HOBr+ Hypobromous acid cation 3 A' 851 1006 0.8459 36.99 1.33 27.8586 15.20 6.73 2.2576
C3+ carbon trimer cation 3 Πu 145i 290 -0.4999 17.74 1.28 13.8740 12.00 12.00 1.0000
C3+ carbon trimer cation 3 Πu 145i 290 -0.4999 17.74 1.28 13.8740 12.00 12.00 1.0000
C3+ carbon trimer cation 2 Σu 2496 2909 0.8580 3932.18 9050.54 0.4345 12.00 12.00 1.0000
NCN NCN 3 Πu 376 501 0.7506 13.67 24.22 0.5646 12.54 12.54 1.0000
NCN NCN 3 Πu 376 501 0.7506 13.67 24.22 0.5646 12.54 12.54 1.0000
N3 azide radical 2 Σu 1705 5923 0.2878 654.41 0.00   14.00 14.00 1.0000
N2O+ Nitrous oxide cation 1 Σ 2140 3290 0.6504 1.06 56.86 0.0187 14.00 14.01 0.9996
N2O+ Nitrous oxide cation 3 Π 509 643 0.7914 3.58 1.73 2.0712 14.24 14.23 1.0002
N2O+ Nitrous oxide cation 3 Π 421 500 0.8430 4.53 2.21 2.0500 14.24 14.23 1.0002
O3- Ozone anion 1 A1 1221 1368 0.8925 2.14 5.88 0.3645 15.99 15.99 1.0000
O3 Ozone 3 B2 1454 2379 0.6112 786.18 1482.27 0.5304 15.99 15.99 1.0000
O3+ Ozone cation 3 B2 1207 2986 0.4043 614.36 203.71 3.0159 15.99 15.99 1.0000
NO2 Nitrogen dioxide 3 B2 1880 2271 0.8280 757.08 1964.08 0.3855 14.62 14.62 0.9995
NCO isocyanato radical 1 Σ 1959 2509 0.7805 20.16 1008.35 0.0200 12.73 13.00 0.9796
PO2 Phosphorus dioxide 3 B2 1457 1620 0.8994 146.71 379.92 0.3862 20.67 20.71 0.9980
CS2+ Carbon disulfide cation 3 Πu 311 362 0.8569 0.66 2.07 0.3175 13.31 13.31 1.0000
OCS+ Carbonyl sulfide cation 1 Σ 2361 3119 0.7570 209.49 2772.23 0.0756 13.41 13.23 1.0133
SO2+ Sulfur dioxide cation 3 B2 1845 3916 0.4712 874.03 42541.27 0.0205 20.65 20.83 0.9912
S3- Sulfur trimer anion 3 B2 519 798 0.6499 959.81 25.31 37.9263 31.97 31.97 1.0000
SF2- sulfur difluoride anion 2 Σu 475 563 0.8432 675.27 507.48 1.3306 24.37 24.37 1.0000
SCN thiocyanato radical 1 Σ 2029 2560 0.7925 34.45 1.38 24.9512 12.80 12.87 0.9948
SCN thiocyanato radical 3 Π 359 408 0.8800 6.79 8.69 0.7805 12.77 12.77 1.0004
NNS Nitrogen sulfide 2 Σ 586 845 0.6934 44.93 28.15 1.5959 18.99 18.87 1.0062
CCl2- dichloromethylene anion 3 B2 332 477 0.6944 451.65 270.22 1.6714 13.99 13.98 1.0006
ClOO chloroperoxy radical 2 A' 715 1092 0.6542 18.30 33.36 0.5486 17.47 17.03 1.0259
ClOO chloroperoxy radical 1 A' 1191 1729 0.6893 24.25 139.43 0.1739 16.07 18.09 0.8884
Cl3- trichloride anion 2 Σu 48 292 0.1636 975.99 470.37 2.0749 34.97 34.97 1.0000
AsO2 Aresenic dioxide 3 B2 1312 6462 0.2031 1064.19 0.00   19.90 20.22 0.9844
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
BH3+ boron trihydride cation 6 B2 312 507 0.6158 119.77 55.86 2.1440 1.23 1.21 1.0135
CH3 Methyl radical 2 A2" 308 398 0.7730 83.24 94.03 0.8852   1.24  
AlH3+ aluminum trihydride cation 3 A1 194 274 0.7101 64.81 82.61 0.7845 1.06 1.07 0.9938
H2CN H2CN 2 A1 1639 2077 0.7893 12.22 13.23 0.9240 1.77 8.94 0.1980
H2CN H2CN 4 B1 1032 1172 0.8806 31.84 32.23 0.9878 1.35 1.36 0.9878
HCNH HCNH 3 A' 1704 2528 0.6740 10.87 490.70 0.0222 7.73 4.49 1.7221
H2O2+ Hydrogen peroxide cation 5 Bu 3689 5812 0.6347 1219.06 888014.90 0.0014 1.07 1.07 1.0000
HNO2+ nitrous acid cation 2 A' 1562 3056 0.5111 114.83 3048.57 0.0377 1.30 11.23 0.1156
HNO2+ nitrous acid cation 5 A' 445 713 0.6250 15.99 6.30 2.5396 8.84 6.20 1.4247
HCCO ketenyl radical 5 A' 95 618 0.1537 168.96 29.38 5.7504 1.45 9.74 0.1486
HCCO ketenyl radical 2 A' 2092 2469 0.8475 89.18 1048.73 0.0850 9.10 11.73 0.7761
HCCO ketenyl radical 4 A' 619 690 0.8973 2.10 158.86 0.0132 4.01 1.30 3.0932
HOClO Chlorous acid 3 A 866 1168 0.7411 92.19 85.68 1.0760 17.88 10.79 1.6566
C4+ Carbon tetramer cation 3 Σu 1337 1509 0.8860 114.49 2250.05 0.0509 12.00 12.00 1.0000
C2N2+ Cyanogen cation 4 Πg 571 641 0.8896 0.00 0.00   12.18 12.18 1.0001
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C2H3 vinyl 4 A' 1635 1858 0.8796 1.49 2.31 0.6450 1.50 5.76 0.2611
C2H3 vinyl 9 A" 885 993 0.8914 2.47 10.49 0.2354 1.27 1.27 0.9986
CH2OH Hydroxymethyl radical 9 A 412 462 0.8922 141.85 120.54 1.1768 1.08 1.08 0.9964
CuCH3 monomethyl copper 3 A1 573 724 0.7908 44.88 38.79 1.1569 4.10 3.51 1.1684
Mg(OH)2 Magnesium dihydroxide 8 B 217 364 0.5949 369.12 309.37 1.1931 1.76 1.31 1.3463
Mg(OH)2 Magnesium dihydroxide 3 A 218 366 0.5961 108.99 40.42 2.6967 1.39 1.43 0.9712
Mg(OH)2 Magnesium dihydroxide 5 A 74 110 0.6712 212.00 158.65 1.3363 1.08 1.08 0.9962
HCCCN+ Cyanoacetylene cation 2 Σ 2011 3286 0.6120 100.07 35.47 2.8217 7.49 1.23 6.0943
HCCCN+ Cyanoacetylene cation 3 Σ 1716 2481 0.6918 428.74 717.54 0.5975 11.71 6.19 1.8908
HCCCN+ Cyanoacetylene cation 6 Π 489 646 0.7577 3.81 0.12 31.0204 7.78 11.81 0.6590
HCCCN+ Cyanoacetylene cation 1 Σ 3510 4252 0.8255 201.13 4107.33 0.0490 1.13 7.75 0.1461
HCCCN+ Cyanoacetylene cation 7 Π 224 260 0.8612 0.02 0.49 0.0329 5.33 5.42 0.9825
HCCCN+ Cyanoacetylene cation 7 Π 223 255 0.8731 0.22 0.42 0.5237 6.18 4.64 1.3325
HSO3 HOSO2 4 A 915 1144 0.8005 241.57 60.61 3.9859 16.58 11.40 1.4547
HSO3 HOSO2 8 A 363 413 0.8781 15.04 16.56 0.9086 4.67 13.50 0.3457
C3O2 Carbon suboxide 7 Πu 86 106 0.8133 0.57 0.01 40.1972 13.28 13.29 0.9988
C3O2 Carbon suboxide 7 Πu 86 106 0.8133 0.57 0.01 40.1972 13.28 13.29 0.9988
N2O3 Dinitrogen trioxide 9 A" 116 175 0.6612 1.66 0.14 11.5523 14.93 15.09 0.9892
F3NO Nitrogen trifluoride oxide 1 A1 1665 1912 0.8707 682.50 516.25 1.3220 14.74 14.77 0.9979
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
CH3OH+ Methyl alcohol cation 12 A 68 229 0.2966 144.20 231.03 0.6241 1.12 1.07 1.0436
H2OH2O water dimer 7 A' 182 213 0.8528 116.84 167.70 0.6967 3.49 3.17 1.1011
H2OH2O water dimer 11 A" 142 161 0.8804 157.19 182.04 0.8635 1.07 1.07 0.9972
H2OH2O water dimer 6 A' 383 435 0.8804 94.95 41.21 2.3039 1.10 1.08 1.0192
CH3CN+ Acetonitrile cation 3 A' 2213 2927 0.7561 80.86 167.49 0.4828 12.22 1.11 10.9643
CHONH2 formamide 12 A 109 207 0.5277 334.92 305.41 1.0966 1.22 1.22 0.9993
CH2CHO Vinyloxy radical 4 A' 1614 1938 0.8329 10.39 308.50 0.0337 1.28 10.21 0.1251
N2O4 Dinitrogen tetroxide 4 Au 65 105 0.6227 0.00 0.00   15.99 15.99 1.0000
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
H2ONH3 Water Ammonia Dimer 9 A' 185 209 0.8838 19.89 13.99 1.4215 2.62 3.26 0.8037
CH3CHN methylmethaniminyl radical 4 A' 1676 2123 0.7894 7.88 65.22 0.1209 2.47 10.52 0.2349
CH3CHN methylmethaniminyl radical 15 A" 179 200 0.8912 2.15 2.07 1.0404 1.25 1.26 0.9968
H2OH2CO water formaldehyde dimer 15 A 116 152 0.7604 46.36 32.88 1.4099 3.35 3.60 0.9310
H2OH2CO water formaldehyde dimer 14 A 132 167 0.7883 123.06 114.73 1.0726 1.07 1.09 0.9891
H2OH2CO water formaldehyde dimer 12 A 191 228 0.8353 27.62 40.91 0.6750 1.10 1.08 1.0130
H2OH2CO water formaldehyde dimer 13 A 174 197 0.8804 32.01 35.06 0.9132 4.12 4.38 0.9404
H2OH2CO water formaldehyde dimer 10 A 524 591 0.8867 246.88 247.56 0.9972 1.06 1.05 1.0096
C3H3N+ acrylonitrile cation 4 A' 2072 2631 0.7873 445.82 1644.94 0.2710 11.93 12.49 0.9555
CH3NO2 Methane, nitro- 15 A" 20 28 0.6981 0.02 0.05 0.4491 1.10 1.09 1.0019
N2O5 Dinitrogen pentoxide 15 A" 27 39 0.6876 0.67 0.00 2228.0000 15.95 15.96 0.9997
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
BH3NH3 borane ammonia 5 A1 605 673 0.8982 34.64 14.32 2.4183 4.97 4.72 1.0517
CH3CHCH 1-propenyl radical 18 A" 184 218 0.8446 0.02 0.01 3.0441 1.25 1.25 0.9987
CH3CHCH 1-propenyl radical 5 A' 1659 1921 0.8639 2.76 3.55 0.7767 1.48 6.84 0.2157
HCOOHH2O Formic acid water dimer 15 A 247 304 0.8108 77.83 81.33 0.9570 1.20 1.14 1.0586
HCOOHH2O Formic acid water dimer 18 A 166 197 0.8400 7.98 8.41 0.9486 4.26 2.21 1.9290
HCOOHH2O Formic acid water dimer 16 A 218 251 0.8673 29.89 40.89 0.7310 6.55 6.41 1.0213
HCOOHH2O Formic acid water dimer 17 A 179 203 0.8813 52.74 25.96 2.0313 1.67 3.37 0.4967
HCOOHH2O Formic acid water dimer 13 A 578 656 0.8819 244.33 170.20 1.4356 1.12 1.48 0.7604
H2OHCOOH Water formic acid dimer 1 15 A 134 174 0.7704 92.56 96.20 0.9621 1.12 1.05 1.0763
H2OHCOOH Water formic acid dimer 1 17 A 88 109 0.8084 32.30 15.35 2.1041 5.37 6.93 0.7749
H2OHCOOH Water formic acid dimer 1 16 A 119 146 0.8127 6.91 0.42 16.3887 5.40 6.96 0.7749
H2OHCOOH Water formic acid dimer 1 13 A 378 457 0.8276 234.86 261.45 0.8983 1.08 1.05 1.0219
H2OHCOOH Water formic acid dimer 1 18 A 64 77 0.8354 9.61 12.57 0.7643 2.03 2.02 1.0065
H2OHCOOH Water formic acid dimer 2 17 A 88 112 0.7892 16.87 15.20 1.1097 5.50 6.56 0.8382
H2OHCOOH Water formic acid dimer 2 15 A 162 203 0.8012 85.72 116.32 0.7370 1.57 1.12 1.3940
H2OHCOOH Water formic acid dimer 2 18 A 82 100 0.8145 15.96 14.46 1.1037 1.94 1.82 1.0608
H2OHCOOH Water formic acid dimer 2 16 A 155 175 0.8855 37.57 0.97 38.7329 2.39 7.08 0.3383
NH2CSNH2 Thiourea 9 A 234 391 0.6001 88.47 157.62 0.5613 1.15 1.13 1.0199
NH2CSNH2 Thiourea 18 B 363 414 0.8765 549.21 1.93 285.2027 1.19 3.83 0.3108
C2H2N4 sym-tetrazine 13 B2u 886 1079 0.8212 99.92 29.55 3.3820 13.25 3.62 3.6589
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C2H7+ Ethane, protonated 21 A 160 270 0.5904 0.87 5.74 0.1512 1.01 1.01 0.9987
C2H7+ Ethane, protonated 11 A 199 254 0.7815 0.36 1.71 0.2081 1.03 1.04 0.9910
C2H7+ Ethane, protonated 10 A 286 356 0.8036 4.02 4.87 0.8256 3.39 4.50 0.7536
C2H7+ Ethane, protonated 4 A 1872 2112 0.8861 8.93 45.93 0.1945 1.10 1.10 1.0040
CH3OHH2O methanol water dimer 11 A' 267 309 0.8657 282.69 280.78 1.0068 1.41 1.35 1.0442
CH3OHH2O methanol water dimer 12 A' 162 186 0.8703 13.96 6.81 2.0513 3.63 3.87 0.9395
CH3OHH2O methanol water dimer 20 A" 90 101 0.8914 10.55 32.29 0.3266 1.02 1.03 0.9892
CH3CONH2 Acetamide 20 A 229 326 0.7014 306.40 268.49 1.1412 1.23 1.24 0.9885
C3H5Cl 1-Propene, 3-chloro- 19 A 435 531 0.8182 1.24 2.22 0.5590 2.31 3.17 0.7289
C3H5Cl 1-Propene, 3-chloro- 21 A 113 136 0.8320 0.54 1.84 0.2934 2.93 1.72 1.7065
C4H4N pyrrolide radical 21 B2 977i 899 -1.0867 802.90 7.04 114.0688 10.78 4.46 2.4161
C4H4N pyrrolide radical 15 B2 3423 58399 0.0586 25.25 0.00   1.09 12.19 0.0895
C4H4N pyrrolide radical 17 B2 1465 3270 0.4480 68.88 79.59 0.8655 1.73 1.09 1.5937
C4H4N pyrrolide radical 19 B2 1117 1327 0.8421 0.68 44.06 0.0153 2.84 1.22 2.3330
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
CH6N3+ guanidinium 4 A1 96 329 0.2925 0.00 0.00   1.01 1.01 1.0000
CH3COCH3 Acetone 12 A2 51 60 0.8521 0.00 0.00   1.02 1.02 0.9994
C3H6S Thietane 14 A' 129 191 0.6724 1.78 1.74 1.0254 1.77 1.77 0.9968
CH3CSCH3 Thioacetone 12 A2 80 102 0.7800 0.00 0.00   1.02 1.02 0.9984
CH2CHCONH2 Acrylamide 23 A 180 286 0.6301 254.08 6.55 38.8197 1.51 3.22 0.4688
C6H4 Benzyne 24 B2 316 591 0.5343 189.90 10.12 18.7737 10.75 9.54 1.1269
C4H4N2 Pyrazine 17 B2u 1203 1365 0.8816 0.90 0.14 6.6050 2.19 7.73 0.2828
C2H4CO3 Ethylene carbonate 12 A 74 179 0.4115 0.48 0.99 0.4828 2.18 2.15 1.0130
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C4H6O Furan, 2,3-dihydro- 27 A 66 164 0.4027 2.74 2.10 1.3065 1.99 1.98 1.0069
C4H6S Thiophene, 2,3-dihydro- 27 A 158 189 0.8380 1.44 1.35 1.0689 1.99 2.00 0.9975
C6H5 phenyl 13 A2 404 469 0.8608 0.00 0.00   2.87 3.00 0.9597
C6H5 phenyl 12 A2 850 975 0.8720 0.00 0.00   1.25 1.25 1.0046
C6H5 phenyl 21 B2 1666 1892 0.8806 0.79 7.92 0.0994 3.69 8.44 0.4374
C6H5 phenyl 18 B1 436 493 0.8843 2.46 5.43 0.4536 3.58 3.74 0.9553
C6H5 phenyl 4 A1 1639 1836 0.8928 0.69 2.37 0.2891 2.88 7.51 0.3843
C6H5 phenyl 15 B1 920 1024 0.8986 0.75 0.73 1.0198 1.32 1.28 1.0339
C3H5Cl3 Propane, 1,2,3-trichloro- 27 A" 17 29 0.6029 1.76 1.18 1.4865 2.70 2.68 1.0063
Fe(CO)5 Iron pentacarbonyl 5 A1 262 595 0.4406 42.05 146.56 0.2869 14.11 14.24 0.9907
Fe(CO)5 Iron pentacarbonyl 4 A1 370 631 0.5854 31.94 81.33 0.3928 16.09 16.63 0.9676
Fe(CO)5 Iron pentacarbonyl 7 A2 287 488 0.5884 0.00 0.00   12.74 12.67 1.0062
Fe(CO)5 Iron pentacarbonyl 11 B2 394 659 0.5975 0.00 0.00   13.13 14.29 0.9187
Fe(CO)5 Iron pentacarbonyl 3 A1 493 786 0.6272 119.10 98.82 1.2052 15.89 15.54 1.0231
Fe(CO)5 Iron pentacarbonyl 17 E 373 588 0.6332 193.54 3.89 49.7852 17.32 13.71 1.2634
Fe(CO)5 Iron pentacarbonyl 17 E 373 588 0.6332 193.54 3.89 49.7857 17.32 13.71 1.2634
Fe(CO)5 Iron pentacarbonyl 12 B2 198 310 0.6399 0.00 0.00   13.54 14.27 0.9486
Fe(CO)5 Iron pentacarbonyl 15 E 535 806 0.6635 13.70 866.80 0.0158 15.51 17.14 0.9049
Fe(CO)5 Iron pentacarbonyl 15 E 535 806 0.6635 13.70 866.80 0.0158 15.51 17.14 0.9049
Fe(CO)5 Iron pentacarbonyl 18 E 318 428 0.7417 1.07 0.30 3.5604 12.72 12.75 0.9981
Fe(CO)5 Iron pentacarbonyl 18 E 318 428 0.7417 1.07 0.30 3.5590 12.72 12.75 0.9981
Fe(CO)5 Iron pentacarbonyl 16 E 476 616 0.7724 78.15 60.27 1.2966 12.42 14.12 0.8801
Fe(CO)5 Iron pentacarbonyl 16 E 476 616 0.7724 78.15 60.27 1.2966 12.42 14.12 0.8801
Fe(CO)5 Iron pentacarbonyl 8 B1 518 651 0.7955 0.00 0.00   12.21 12.27 0.9951
Fe(CO)5 Iron pentacarbonyl 19 E 100 122 0.8220 7.71 16.78 0.4593 17.40 16.76 1.0380
Fe(CO)5 Iron pentacarbonyl 19 E 100 122 0.8220 7.71 16.78 0.4593 17.40 16.76 1.0380
Fe(CO)5 Iron pentacarbonyl 9 B1 98 110 0.8893 0.00 0.00   15.63 15.53 1.0063
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
H2OCH3OCH3 water dimethylether dimer 29 A 55 88 0.6172 9.69 11.38 0.8511 2.83 2.99 0.9465
H2OCH3OCH3 water dimethylether dimer 28 A 137 162 0.8440 99.81 108.96 0.9160 1.26 1.14 1.1090
H2OCH3OCH3 water dimethylether dimer 27 A 145 171 0.8463 30.94 17.52 1.7660 2.91 3.35 0.8686
H2OCH3OCH3 water dimethylether dimer 24 A 290 326 0.8899 80.87 89.87 0.8998 1.21 1.14 1.0683
H2OCH3OCH3 water dimethylether dimer 22 A 582 652 0.8927 177.07 183.03 0.9674 1.04 1.04 1.0028
C3H7NO Propanamide 27 A 276 328 0.8407 10.36 264.54 0.0392 3.30 1.25 2.6360
C3H7NO Propanamide 28 A 235 265 0.8873 44.00 9.25 4.7559 1.09 3.29 0.3304
C2H6N2O2 Dimethylnitroamine 29 A 143 170 0.8458 5.09 3.84 1.3264 1.34 1.18 1.1371
CH6N4S Carbonothioic dihydrazide 30 A 55 84 0.6532 13.04 38.38 0.3397 3.89 3.07 1.2659
C4H6OS 4,5-dihydrothiophene-3-ol 29 A 216 243 0.8877 146.66 42.24 3.4718 1.14 2.93 0.3886
C4H6OS 4,5-dihydrothiophene-3-ol 30 A 159 179 0.8907 9.14 8.62 1.0605 1.96 2.16 0.9087
C4H6OS 4,5-dihydrothiophene-2-ol 30 A 156 177 0.8808 1.77 2.90 0.6108 2.39 2.75 0.8679
C4H6OS 2,3-dihydrothiophene-2-ol 30 A 77 90 0.8576 2.09 1.76 1.1908 2.97 2.99 0.9931
C5H5NO 3-Pyridinol 29 A" 300 354 0.8459 147.52 141.75 1.0407 1.22 1.11 1.1031
C5H5NO 2(3H)-Pyridinone 30 A 38 95 0.3998 2.58 2.01 1.2829 3.36 4.29 0.7839
C6H4F2 1,4-difluorobenzene 20 B2u 1276 1449 0.8803 0.66 0.24 2.7155 3.69 5.97 0.6186
C6F6 hexafluorobenzene 9 B2u 1206 1448 0.8331 0.00 0.00   12.00 12.00 1.0003
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C5H8 Cyclopentene 18 A' 150 183 0.8207 0.11 0.16 0.6904 1.60 1.60 1.0022
C5H8 Cyclobutane, methylene- 19 A' 99 120 0.8224 0.02 0.13 0.1233 1.87 2.02 0.9274
C2H3OC2H5 Ethene, ethoxy- 33 A 51 69 0.7388 1.37 1.54 0.8925 2.10 2.13 0.9860
CH2C(CH3)OCH3 1-Propene, 2-methoxy- 33 A 66 83 0.7875 7.48 7.67 0.9757 2.53 2.81 0.8983
C3H7ONO Propyl nitrite 33 A 42 63 0.6697 0.57 0.05 11.6523 6.59 5.58 1.1827
C3H7ONO Propyl nitrite 30 A 211 260 0.8104 0.62 1.20 0.5168 5.62 1.56 3.6017
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C4H9N Cyclobutylamine 21 A' 165 206 0.8029 1.57 2.10 0.7457 1.99 2.05 0.9680
C6H8 3-Methylenecyclopentene 36 A 12 82 0.1407 0.02 0.12 0.1296 1.90 1.97 0.9630
C4H8O2 1,3-Dioxolane, 2-methyl- 35 A 215 240 0.8941 3.77 2.17 1.7404 1.96 1.39 1.4123
N(CH3)2CONH2 Urea, N,N-dimethyl- 35 A 106 128 0.8300 6.56 0.81 8.1024 2.15 1.52 1.4088
C5H8O Furan, 2,3-dihydro-5-methyl- 36 A 75 161 0.4632 2.59 1.23 2.1101 1.97 1.48 1.3279
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C4H9NO Butanamide 35 A 261 316 0.8255 0.61 259.96 0.0024 1.08 1.25 0.8583
C6H5CH3 toluene 39 A" 16 59 0.2795 0.17 0.20 0.8122 1.04 1.04 1.0002
C5H8O2 Acetylacetone 20 A 48 61 0.7847 9.40 6.91 1.3612 4.65 4.85 0.9589
C5H8O2 Acetylacetone 39 B 56 70 0.7990 13.69 11.50 1.1901 3.86 3.99 0.9666
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C5H11 2-Methylbut-2-yl radical 42 A 50 69 0.7201 0.04 0.07 0.5548 1.83 1.89 0.9685
C6H10 Cyclopentene, 1-methyl- 42 A 142 165 0.8624 0.06 0.13 0.4308 1.66 1.73 0.9614
C6H10 3-Hexyne 15 A 1059 3140 0.3372 0.01 0.00   2.29 1.10 2.0775
C6H10 3-Hexyne 14 A 1188 3212 0.3697 0.32 0.00   1.71 1.10 1.5468
C6H10 3-Hexyne 19 A 335 803 0.4175 4.64 0.00   1.96 1.16 1.6973
C6H10 3-Hexyne 40 A 402 961 0.4186 3.99 0.31 12.8965 2.74 2.14 1.2803
C6H10 3-Hexyne 33 A 1409 3096 0.4552 0.02 26.67 0.0006 1.15 1.06 1.0849
C6H10 3-Hexyne 32 A 1496 3112 0.4808 51.39 21.21 2.4230 1.56 1.04 1.5024
C6H10 3-Hexyne 31 A 1563 3202 0.4881 1.31 46.71 0.0280 1.25 1.10 1.1339
C6H10 3-Hexyne 41 A 250 502 0.4987 0.02 0.88 0.0206 1.18 4.14 0.2854
C6H10 3-Hexyne 18 A 567 1123 0.5046 0.46 0.00   4.92 1.37 3.5953
C6H10 3-Hexyne 39 A 575 1115 0.5155 2.66 5.73 0.4647 4.02 2.02 1.9868
C6H10 3-Hexyne 16 A 854 1559 0.5477 1.13 0.00   1.17 1.04 1.1188
C6H10 3-Hexyne 17 A 743 1325 0.5606 0.14 0.00   2.84 1.17 2.4210
C6H10 3-Hexyne 21 A 141 203 0.6942 2.61 0.00   2.19 1.63 1.3425
C6H10 3-Hexyne 37 A 988 1398 0.7063 0.24 41.18 0.0058 2.33 1.77 1.3201
C6H10 3-Hexyne 38 A 855 1198 0.7131 0.53 0.41 1.2813 1.18 2.28 0.5172
C6H10 3-Hexyne 20 A 237 328 0.7238 0.30 0.00   1.48 1.87 0.7929
C6H10 3-Hexyne 42 A 127 172 0.7424 2.46 0.08 31.0164 2.64 3.95 0.6675
C6H10 3-Hexyne 35 A 1214 1545 0.7857 0.31 1.28 0.2451 1.49 1.07 1.3929
C6H10 3-Hexyne 34 A 1235 1568 0.7875 6.88 2.97 2.3138 2.23 1.06 2.1026
C6H10 3-Hexyne 36 A 1173 1467 0.7999 1.80 0.37 4.8484 2.20 1.24 1.7781
C6H10 Cyclopentene, 4-methyl- 42 A 117 131 0.8969 0.04 0.03 1.1207 2.20 2.18 1.0117
C5H10O 3-Pentanone 21 A2 27 31 0.8912 0.00 0.00   1.59 1.58 1.0035
C5H10O Oxetane, 3,3-dimethyl- 24 A' 51 139 0.3654 7.14 6.88 1.0366 3.20 3.24 0.9871
C6H5CHCH2 Styrene 42 A 58 82 0.7058 0.09 0.13 0.6522 2.37 2.55 0.9289
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C6H12 Pentane, 3-methylene- 24 A 34 1388 0.0244 0.01 2.64 0.0019 2.29 1.39 1.6487
C6H12 Pentane, 3-methylene- 23 A 243 1407 0.1730 0.00 0.35 0.0006 1.06 2.06 0.5148
C6H12 Pentane, 3-methylene- 22 A 286 1465 0.1953 0.11 5.64 0.0194 2.37 1.24 1.9045
C6H12 Pentane, 3-methylene- 21 A 475 1465 0.3245 0.46 1.54 0.2960 2.21 1.23 1.7982
C6H12 Pentane, 3-methylene- 12 A 1559 3093 0.5042 0.38 32.29 0.0117 1.23 1.06 1.1631
C6H12 Pentane, 3-methylene- 20 A 772 1499 0.5148 0.03 2.04 0.0123 1.96 1.20 1.6388
C6H12 Pentane, 3-methylene- 11 A 1598 3094 0.5163 0.95 0.00 595.6876 1.19 1.06 1.1191
C6H12 Pentane, 3-methylene- 10 A 1635 3106 0.5263 5.38 17.64 0.3050 1.06 1.04 1.0262
C6H12 Pentane, 3-methylene- 8 A 1661 3143 0.5284 0.02 15.10 0.0016 1.09 1.10 0.9853
C6H12 Pentane, 3-methylene- 9 A 1646 3107 0.5298 3.29 28.98 0.1137 1.04 1.04 1.0069
C6H12 Pentane, 3-methylene- 19 A 821 1546 0.5311 0.01 3.93 0.0034 1.23 1.07 1.1513
C6H12 Pentane, 3-methylene- 18 A 875 1550 0.5645 1.86 8.05 0.2310 1.18 1.07 1.0982
C6H12 Pentane, 3-methylene- 7 A 1875 3143 0.5965 16.13 19.23 0.8385 4.88 1.10 4.4288
C6H12 Pentane, 3-methylene- 17 A 1072 1565 0.6853 0.00 12.26 0.0000 2.22 1.07 2.0767
C6H12 Pentane, 3-methylene- 16 A 1173 1566 0.7488 0.75 4.43 0.1683 1.59 1.04 1.5230
C6H12 Pentane, 3-methylene- 15 A 1228 1567 0.7834 1.68 0.51 3.2889 1.53 1.04 1.4667
C6H12 Pentane, 3-methylene- 13 A 1487 1732 0.8583 7.81 5.72 1.3669 1.37 4.99 0.2741
C6H12 Pentane, 3-methylene- 14 A 1405 1576 0.8920 0.28 0.86 0.3211 1.18 1.07 1.0985
C6H12 trans-1,3-dimethylcyclobutane 28 A' 103 129 0.7977 0.01 0.02 0.2637 2.44 2.47 0.9908
C6H12 Cyclobutane, ethyl- 47 A 138 173 0.8024 0.00 0.02 0.2105 1.71 1.72 0.9964
C4H6(CH3)2 dimethylcyclobutane A' 148 190 0.7813 0.00 0.01 0.1875 1.91 1.94 0.9811
C5H12S 1-Butanethiol, 2-methyl- 48 A 57 65 0.8642 8.03 6.74 1.1913 2.28 2.27 1.0046
C5H12S 2-Butanethiol, 3-methyl- 48 A 61 68 0.8982 2.26 1.88 1.2033 2.77 2.71 1.0203
Formula Name Mode Number Symmetry Frequency (cm-1) IR Intensity (km mol-1) Reduced mass
HF MP2 ratio HF MP2 ratio HF MP2 ratio
C8H14 Bicyclo[2.2.2]octane 11 A1 26 125 0.2101 0.00 0.00   1.73 1.75 0.9923