Variational treatment of the vibrational Hamiltonian for NH3 and H2NO

The full vibrational Hamiltonian for the inversion of NH3 and H2NO has been diagonalized in a basis set that is the direct product of functions of the inversion coordinate and of harmonic vibrational functions independent of this inversion coordinate. The kinetic part of the Hamiltonian matrix is constructed with the use of the closure relation for these vibrational functions. The method is tested with the potential function which is supposed to be harmonic for the vibrations orthogonal to the inversion coordinate: the first computed levels are in good agreement with experimental levels for NH3. For higher levels, anharmonic terms should be included. (C) 2002 Wiley Periodicals, Inc.