Two-dimensional model of intramolecular hydrogen bond

One- and two-dimensional vibrational problems were solved to determine the states of H and D in the intramolecular hydrogen bond of malonic dialdehyde. Within the one-dimensional approach the model potential (barrier height 51 kJ/mol) satisfied with the IR and microwave spectroscopy data. For the two-dimensional problem an approach to evaluation of eigenvalues with high accuracy based on the Ritz method was developed. Within the two-dimensional approximation the barrier height was taken to be 57 kJ/mol. An introduction of the second dimension was found to give rise to the vibrational non-adiabatic effects.