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Bad vibrational frequency predictions

19 02 11 15 45

Calculated frequencies that differ from experiment by more than 400 cm-1 or have a ratio with experiment outside of 0.7 to 1.2 are listed

Calculated vibrational frequencies ("theory" in table) are calculated at QCISD(TQ)/3-21G*
Calculated values were scaled by 1.

Species Name mode int rot Symmetry Experiment Theory difference ratio
CO2 Carbon dioxide 3 Πu 667 551 -116 1.211
O2 Oxygen diatomic 1 Σg 1556 1268 -288 1.227
NO Nitric oxide 1 Σ 1876 1352 -524 1.388
C2H2 Acetylene 4 Πg 612 480 -132 1.275