Atomare und elektronische Struktur komplexer 13/15-Halbleiter sowie ausgewählte Eigenschaften weiterer Halbleiter

In this thesis, three main topics have been adressed: (1) the theoretical description and explanation of the infrared activity of naphthalene tetracarboxylic acid dianhydride (NTCDA) adsorbed on a silver surface due to a dynamical charge transfer, (2) the computation of temperature and pressure dependent coverage of a Si(001) surface in a hydrogen flow based on various models (ab initio thermodynamics, phonon computations) and (3) the electronic structure of complex 13/15 semiconductors with the goal to compute accurate band structures as a starting point for the computation of optical properties. For the first topic, an ab initio proof of interfacial dynamic charge transfer as reason for IR activity of certain vibrational modes for NTCDA/Ag(111) could be given, fitting with experimental evidence and model calculations. This was achieved by analyzing partial densities of states and partial charges of displaced structures. As second topic, the coverage of the Si(001) surface with hydrogen under the conditions present in epitaxy procedures was studied. Comparing different approaches, the computation of surface phonons for the pristine and monolayer-covered surface and interpolation for intermediate coverages showed good agreement with experimental studies. These results can be used as a starting point for adsorption studies under epitaxy conditions. Finally, a procedure has been implemented to compute the band structures of complex 13/15-semiconductors and determine parameters in the framework of kp-theory. To this end, the band structures of supercells are unfolded first. Then, the parameters which reproduce the band structure best are determined by variation. These can be adapted to allow the computation of optical properties for quantum well superstructures. In this context, the band gaps of dilute nitrides, which have been a challenge to computation for some time, could be opened to computation.