Large Amplitude Motions of Pyruvic Acid (CH3-CO-COOH).
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ABSTRACT: Torsional and rotational spectroscopic properties of pyruvic acid are determined using highly correlated ab initio methods and combining two different theoretical approaches: Second order perturbation theory and a variational procedure in three-dimensions. Four equilibrium geometries of pyruvic acid, Tc, Tt, Ct, and CC, outcome from a search with CCSD(T)-F12. All of them can be classified in the Cs point group. The variational calculations are performed considering the three internal rotation modes responsible for the non-rigidity as independent coordinates. More than 50 torsional energy levels (including torsional subcomponents) are localized in the 406-986 cm-1 region and represent excitations of the ν24 (skeletal torsion) and the ν23 (methyl torsion) modes. The third independent variable, the OH torsion, interacts strongly with ν23. The A1/E splitting of the ground vibrational state has been evaluated to be 0.024 cm-1 as it was expected given the high of the methyl torsional barrier (338 cm-1). A very good agreement with respect to previous experimental data concerning fundamental frequencies (νCAL - νEXP ~ 1 cm-1), and rotational parameters (B0CAL - B0EXP < 5 MHz), is obtained.
SUBMITTER: Senent ML
PROVIDER: S-EPMC8303138 | biostudies-literature |
REPOSITORIES: biostudies-literature
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