Influence of the vibrational zero-point energy correction on the amine inversion barrier and the far-infrared spectrum of methylamine

The vibrational zero-point energy correction is determined for the methyl torsion and amine hydrogen wagging potential energy function. It is found that the amine inversion barrier increases from 1727.27 cm−1 up to 1850.65 cm−1 which is in better agreement with the value of 1937 cm−1 deduced from experiment. In addition, the splittings calculated for the fundamental band reproduce fairly well the experimental data.