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IV.A.5. Compare Barriers to Internal Rotation for C2H6 (Ethane)

Experimental barrier to internal rotation is 12.2 kJ/mol
Experimental data from Gurvich
V3=1024 cm-1
Energy Differences (Calculated - Experimental) in kJ/mol
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Methods with predefined basis sets
semi-empirical AM1 -7.0
PM3 -6.3
molecular mechanics DREIDING -0.1

Methods with standard basis sets
3-21G 6-31G* 6-31+G** cc-pVTZ aug-cc-pVTZ
hartree fock HF -0.7 0.2 0.1 0.4  
density functional B3LYP -0.9 -0.5 -0.8 -1.2  
3-21G 6-31G* 6-31+G** cc-pVTZ aug-cc-pVTZ
Moller Plesset perturbation MP2 0.3 0.9 1.0 -0.1 -0.2
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.

References

squib reference
Gurvich Gurvich, L.V.; Veyts, I. V.; Alcock, C. B., Thermodynamic Properties of Individual Substances, Fouth Edition, Hemisphere Pub. Co., New York, 1989

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