Accurate mesh truncation for Schrodinger equations by a perfectly matched layer absorber: Application to the calculation of optical spectra

Quasibound and continuum states are of particular importance for the numeri cal investigation of coherence properties and are sensitive with respect to the boundary condition chosen at the edge of the computational window. An open boundary condition will be derived which is particularly suitable for dynamical problems described by Schrodinger-type equations. With this appro ach, bound states as well as unbound states can be described adequately. Th e boundary condition is derived from a perfectly matched layer (PML) formal ism commonly used in the field of electrodynamics. Consequently, the calcul ation domain is reduced leading to a calculation time reduction by orders o f magnitude. From the physical point of view this formulation allows an ade quate analysis of transport phenomena or absorption spectra, e.g., the resu lts obtained by the PML formalism are compared with accurate numerical resu lts calculated using a large mesh and show an excellent performance. For ex ample, the Coulomb enhanced Franz-Keldysh effect is investigated, which can not be analyzed adequately without using proper open boundary conditions. [ S0163-1829(99)51332-5].