+Getting appointed to a professorship at the University of Paderborn, it was also him, who initiated a collaboration with the local theory group under the direction of Prof.\ Dr.\ Wolf Gero Schmidt.
+I would like to thank him for six month of financial support, which allowed me to extend my research period, as well as for his helpful contributions to common articles and respective publishing procedures.
+More importantly, the collaboration involved further investigations based on first-principles calculations, which improved the quality of this work to a great extent.
+At this point, I would like to express special thanks to Dr.\ Eva Rauls.
+The present thesis would not have been possible without her assistance and mentoring with respect to the utilized methods required by the new approach of investigation as well as her expertise in the materials system.
+I am greatly thankful for the possibility to repeatedly visit the theory group in Paderborn.
+In this context, Dr.\ Simone Sanna is acknowledged for respective technical support and Michael Weinl, doctoral student of Prof. J\"org K. N. Lindner back then, for accommodation.