DVR3D: for the fully pointwise calculation of ro-vibrational spectra of triatomic molecules

Abstract

The DVR3D program suite calculates energy levels, wavefunctions, and where appropriate dipole transition moments, for rotating and vibrating triatomic molecules. Potential energy, and where necessary, dipole surfaces must be provided. The programs use an exact (within the Born-Oppenheimer approximation) Hamiltonian, offer a choice of Jacobi or Radau internal coordinates and several body-fixed axes. Rotationally excited states are treated using an efficient two-step algorithm. The programs uses a Discrete Variable Representation (DVR) based on Gauss-Legendre and Gauss-Laguerre quadrature for all 3 internal coordinates and thus yields a fully pointwise representation of the wavefunctions. The vibrational step uses successive diagonalisation and truncation which is implemented for 4 of the 6 possible coordinate orderings. The rotational and transition dipole programs exploit the major savings offered by performing integrals on a DVR grid.