EIGENRESONANCE STATES IN THE KRONIG-PENNEY MODEL

We investigate a sandwich of three layer systems with Dirac F-functions in the Kronig-Penney model. The inner system of N = 5 atomic layers is enclosed by the two outer systems with different potential strength. The number M of the atomic layers in the outer system is varied between M = 8 and infinity, whereas the number N of the inner layers is held fixed. We obtain the transmission coefficient for the finite system in the region of scattering energies (E > 0). An alternating set of transmission gaps, transmission bands and bands of 'eigenresonance' states is obtained. The normalizable 'eigenresonances' occur (for M going to infinity), if a transmission band of the inner system overlaps a transmission gap of the outer systems. The reason for obtaining solutions of standing waves in the band of 'eigenresonances' is the rapid change of the wave phase of a traveling wave, which occurs in a transmission band of the inner system.