RESTARTED KRYLOV-SPACE SPECTRAL FILTERING

A recently developed spectral-filter algorithm, which is based on the iterative application of a Green operator approximated in a finite-ord er Krylov subspace, has been applied to the problem of computing vibra tional eigenstates of a medium-sized molecule. A six-dimensional model Hamiltonian for formaldehyde, H2CO, is used to illustrate the efficie ncy of the method by comparison with restarted Fourier filtering. The Krylov-space algorithm is shown to produce substantial savings in comp utation time in comparison with the Fourier method, indicating that it may prove to be of considerable utility for the investigation of quan tum dynamics in polyatomic unimolecular reactions.