TY - JOUR A1 - Röseler, J. A1 - Hartmann, Michael T1 - An exactly solvable model for the large polaron JF - Zeitschrift für Physik B N2 - We present an exactly diagonalizable model Hamiltonian for the large polaron derived by analyzing the variational ansatz by Haga-Larsen (HL) for the Fröhlich Hamiltonian. The lowest energy eigenvalue of the model Hamiltonian for fixed wave numbers reproduces the energy of the variational ansatz by Haga-Larsen and is, therefore, an upper bound with respect to the corresponding energy eigenvalue of the Fröhlich Hamiltonian. This is valid for any momentum which is proven by extending the Haga-Larsen approach. Furthermore, since all integrations can be performed analytically, the model Hamiltonian is easily tractable. The energy eigenvalue spectrum of the model Hamiltonian is studied below and above the phonon-emission threshold. The quality of the model Hamiltonian is determined by the variational ansatz of Haga and Larsen. Incorporating an improved energy-momentum relation, a generalized model Hamiltonian is derived possessing a larger validity range with respect to the coupling strength. Furthermore, a second exactly diagonalizable model Hamiltonian based on improved Wigner-Brillouin perturbation theory due to Warmenbol, Peeters, and Devreese (WPD) is presented. It is briefly demonstrated that one is able to construct all mentioned model Hamiltonians also in the 2D polaron problem. In contrast to the 3D case, where the HL-type model Hamiltonian possesses the higher quality for any momentum, in the 2D case, it works well only for small momenta. For large momenta, only the WPD-type model Hamiltonian describes the energy-momentum relation correctly. We demonstrate the usefulness of the model Hamiltonian concept by exactly calculating the one-electron Green’s function for all mentioned model Hamiltonians and comment why significant advantages of the model Hamilton concept for the treating of low-dimensional systems (planar semiconducting quantum-well structures) can be expected. KW - Inorganic Chemistry KW - Engineering KW - Condensed Matter Physics Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5782 VL - 102 IS - 4 SP - 531 EP - 540 ER - TY - CHAP A1 - Santos, C. A1 - Suisky, D. A1 - Enders, P. A1 - Neugebauer, F. A1 - Hartmann, Michael A1 - Röseler, J. A1 - Knoch, R. A1 - Heimbrodt, Wolfram T1 - Magnetooptical Anisotropy in Semimagnetic Materials: the Interplay of Strain and Magnetic Field T2 - European Workshop on II-VI Semiconductors, Linz N2 - Keine Angabe - No details KW - Magnetooptical anisotropy KW - Semimagnetic material Y1 - 1994 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - CHAP A1 - Santos, C. A1 - Suisky, D. A1 - Neugebauer, F. A1 - Hartmann, Michael A1 - Heimbrodt, Wolfram A1 - Röseler, J. T1 - Magnetooptical Anisotropy in Superlattices and Quantum Wells T2 - 22nd International Conference on the Physics of Semiconductors, Vancouver N2 - Keine Angabe - No details KW - Engineering Y1 - 1994 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER -