Theoretical ab initio study of O-H vibrational band in gas-phase glycine conformers

The O-H vibrational band has been theoretically studied for the two most stable glycine conformers utilizing our variable effective mass approach. The stretching frequencies of the O-H bond of the most stable gas-phase glycine conformers were predicted. Analytical expressions for the Hamiltonian matrix elements of the vibrational problem were derived. A functional fit to the potential energy term was obtained based on the electronic energies calculated at different O-H bond distances at the MP2 level of theory. The calculated O-H stretching frequencies are in good agreement with the low-temperature IR spectroscopic data.