THE SIMULATION OF OUTGOING-WAVE BOUNDARY-CONDITIONS VIA A SYMMETRICALLY DAMPED, HERMITIAN HAMILTONIAN OPERATOR

A new method for simulating the effect of outgoing-wave boundary condi tions in the calculation of quantum resonances is presented. The Hermi tian Hamiltonian operator H is multiplied on each side by a damping op erator D, consisting of areal function d(R), which is unity in the res onance region and falls gradually to zero in the asymptotic region. Th e spectrum of the symmetrically damped Hamiltonian operator, DHD is sh own to provide an excellent approximation to the resonance energies of the Hamiltonian with outgoing-wave boundary conditions. Applications to the calculation of resonance energies for collinear H+H-2 scatterin g and for HO2 dissociation are presented. In addition, we explore the feasibility of extracting resonance widths by using the DHD operator w ithin a filter diagonalization (FD) scheme. Application of the FD sche me to HO2 yields encouraging results. (C) 1997 American Institute of P hysics. [S0021-9606(97)02447-1].