Computation of the energy levels of large-amplitude low-frequency vibrations. Comparison of the prediagonalized harmonic basis and the prediagonalized distributed Gaussian basis

The formalism involved in the solution of the Schr?dinger equation for twodimensional vibrational potential energy surfaces for large-amplitude low-frequency motions is reviewed. The performance of two different bases, the prediagonalized harmonic basis (PHB) and the prediagonalized distributed Gaussian basis (PDGB), is investigated. The calculated energy levels obtained with the two basis sets are in excellent agreement with one another.