| Abstract
| - Accurate geometries, relative energies, rotational and quarticcentrifugal distortion constants, dipole moments,harmonic vibrational frequencies, and infrared intensities have beendetermined from ab initio calculationsfor 13 conformers, corresponding to minima on the potential energysurface, of the neutral form of the aminoacid α-alanine. The theoretical relative energy predictions,even after zero-point vibrational energy corrections,differ significantly from the experimental lower limits deduced frommillimeter wave spectra. Energetic andstructural results indicate necessary model improvements for agas-phase electron diffraction study of α-alanine.The structural results obtained support the molecular constantsmeasured for two conformers of low relativeenergy. The accurate calculated rotational and quartic centrifugaldistortion constants and vibrational frequencydata for the other conformers should aid in identification of theconformers by rotational and vibrationalspectroscopies, respectively.
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