ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The potential energy function about the C–C single bond for the ground state 1,3-butadiene has been derived from ab initio calculations at both the Hartree–Fock (HF) level with 6-31G, 6-31G*, and 6-311G** basis sets and the second-order Møller–Plesset perturbation (MP2) level with 6-31G* basis set with the complete geometry optimizations at each of 15 fixed CCCC dihedral angles; the total energies and optimized geometries for the s-trans, gauche, and s-cis conformers were also determined at MP2 level with 6-311G* basis set and the third-order Møller–Plesset perturbation (MP3) level with 6-31G* basis set. The second stable conformer of the butadiene is predicted to be a gauche structure from all the calculations with a CCCC dihedral angle between 35° and 40° and a barrier of 0.5–1.0 kcal/mol to the s-cis transition state, and the theoretical torsional potentials are in good agreement with the experimental potential function of trans–gauche–gauche case derived by Durig et al.; by contrast, the theoretical torsional components differ significantly from the experimental results obtained from a trans–cis model. Vibrational frequencies and force field for s-trans and gauche conformers of 1,3-butadiene are determined at the Hartree–Fock and MP2 levels with 6-31G, 6-31G*, 6-311G, and 6-311G* basis sets. The mean absolute percentage deviations of the calculated frequencies from the experimental values (not corrected for anharmonicity) are ∼10%–13% and 3%–6% for the Hartree–Fock and MP2 methods, respectively. The effects of polarization functions and electron correlation on the force fields are studied, and the additivity of correlation and d function effects are discussed. Comparisons are made with other force fields, including experimental and previous ab initio results.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.459739
