Ab initio studies of the conformers and conformational distribution of the gaseous hydroxyamino acid threonine |
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Authors: | Meiling Zhang Zijing Lin |
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Institution: | Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China |
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Abstract: | Systematic and extensive conformational search has been performed to characterize the gas-phase threonine structures. A total of 1296 unique trial structures were generated by allowing for all combinations of internal single-bond rotamers. All the trial structures were optimized at the B3LYP/6-311G* level of the theory and then subjected to further optimization at the B3LYP/6-311++G** level. A total of 71 conformers were found and their rotational constants, dipole moments, zero-point vibrational energies, harmonic frequencies and vertical ionization energies of all the conformers were determined. Single-point energies were also calculated at the MP2/6-311G(2df,p) and B3LYP/6-311G(2df,p) levels. Characteristic H-bonding types were classified and listed for all the conformers. The conformational distributions of gaseous threonine at various temperatures were calculated. |
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Keywords: | Ab initio Threonine conformers Vibrational frequencies Hydrogen bonding Vertical ionization energies Conformational distribution |
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