Archiviertes Physik-Kolloquium:

04. Jul. 2013, 16:15 Uhr, Gebäude TAB-Geb., Am Fallturm 1, Eingang F, EG, Raum Seminarraum 0.50/0.51

Calculation of defects, surfaces and nanostructures of electronic materials

Dr. Peter Deák, BCCMS, Univ. Bremen

The functionality of electronic materials originates very often from defects in the bulk and are influenced by the surface. This is even more true for nanostructures. While band structure methods were highly effective and reasonably accurate for perfect crystals, the treatment of imperfections was and is a challenge for computational solid state physics. From my practical study of defects in SiC around the turn of the millennium, it has become clear to me that standard local and semi-local approximations to density functional theory (DFT) cannot even predict the ground state of many defects reliably. While higher level ab initio methods are to this day still impractical for the study of defects and surfaces, I will show that the application of hybrid functionals in the framework of the generalized Kohn-Sham scheme offers a reasonable alternative in the time being. I will explain why and where hybrids work well, and I will show examples from the fields of my recent research. The latter include TiO2 for photo-catalytic and opto-electronic applications, and color centers in nanodiamonds for application in quantum computing and encryption or biolabeling. My research has led to the prediction of a Dirac-particle-based switching device in TiO2-nanowires, and to the explanation of the environment dependent properties of the spectra of nanodiamonds. After describing these results, I shortly show a few ideas for further work