ℒ² golden rule method to calculate partial widths for the decay of resonance states

We have calculated resonance energies and partial widths for two two-dimensional models of van der Waals molecule predissociation. We use a general method involving only Hamiltonian and overlap integrals in a square integrable (ℒ²) basis set containing a scale parameter. We use a stabilization method with a compactness criterion to find the resonance energies, and a decoupled golden rule method to find the partial widths. The results are compared to accurate energies and partial widths obtained by fitting solutions of the close-coupling equations to multichannel Breit-Wigner expressions. We studied resonances having two open channels for two sets of potential parameters, and in each case we obtained an accuracy of 16% or better for both partial widths by the ℒ² method.