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IV.A.5. Compare Barriers to Internal Rotation for C2H2O2 (Ethanedial)

Experimental barrier to internal rotation is 24.9+- 0.8 kJ/mol
Energy Differences (Calculated - Experimental) in kJ/mol
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Methods with predefined basis sets
semi-empirical AM1 -11.3
PM3 -11.7
PM6 -6.3

Methods with standard basis sets
3-21G 6-31G* 6-31+G** cc-pVTZ aug-cc-pVTZ
hartree fock HF 16.0 5.2 3.2 2.3  
density functional B3LYP 14.8 3.4 0.7 1.0  
wB97X-D   2.8   0.2  
3-21G 6-31G* 6-31+G** cc-pVTZ aug-cc-pVTZ
Moller Plesset perturbation MP2 12.6 4.0 1.0 1.8  
B2PLYP         0.5
Coupled Cluster CCSD   2.9 0.2 0.9  
3-21G 6-31G* 6-31+G** cc-pVTZ aug-cc-pVTZ
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.

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