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IV.A.5. Compare Barriers to Internal Rotation for CHCCH2CH3 (1-Butyne)

Experimental barrier to internal rotation is 12.7 kJ/mol
Experimental data from 1989Gui/Dur:101
V3=1059.5, V6=-30.2 cm-1
Energy Differences (Calculated - Experimental) in kJ/mol
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Methods with predefined basis sets
semi-empirical AM1 -7.1
PM3 -6.7
molecular mechanics DREIDING 2.1

Methods with standard basis sets
3-21G 6-31G* 6-31+G**
hartree fock HF 1.4 1.9 38.5
density functional B3LYP     0.3
3-21G 6-31G* 6-31+G**
Moller Plesset perturbation MP2   2.3 2.1
3-21G 6-31G* 6-31+G**
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
1989Gui/Dur:101 GA Guirgis, JR Durig, S Bell "Torsional Transitions and Barrier to Internal rotation of 1-butyne" J. Mol. Struct. 196 (1989) 101-111

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