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.