Theoretical analysis of the proton transfer and internal rotation in 2-methylmalonaldehyde

•Ab initio calculations of the two dimensional PES were carried out.•Relaxation of geometrical parameters was calculated.•The semi rigid model for the proton tunneling and torsion was applied.•The barriers for the proton transfer and internal rotation were determined.

For the first time ab initio calculations of the two dimensional potential energy surface (PES) and relaxation of geometrical parameters have been carried out for 2-methylmalonaldehyde (2-MMA) at the of MP2/6-311++G∗∗ level using a Gaussian package. The comparison of calculated energies for two selected configurations shows no significant difference between these results and those at the CCSD(T)/6-311++G∗∗ level. The semi rigid model for the proton transfer and torsion has been applied to d0 and d1 isotopologues of 2-MMA. The ab initio PES was modified using the experimental data from the ground vibrational state. The barriers for the proton transfer and the barriers for internal rotation were obtained.

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