Research
Research interests
The group is dealing with ab-initio calculations based on density functional theory (DFT). We focus on code development as well as on their application to a variety of crystalline solids. Below we exemplarily outline three research areas which are linked to the individual project pages. Some information on other research projects can be found here.
Organic Semiconductors.
We focus on the structural, electronic, and optical
properties of molecular semiconductors in the bulk and at interfaces to metals.
We employ a recently developed van-der-Waals density functional to demonstrate
that vdW forces are not only crucial for the binding in organic molecular crystals but also between
organic / metal interfaces
(press release).
We also investigate the electronic band structure of
highly oriented molecular films with DFT and compare to measurements using angle-resolved photoemission
spectroscopy (ARPES). Thereby, we were able to show that
the ARPES signal can be utilized to map the electron distribution of
individual molecular orbitals
(press release).
Alloys.
We are involved in several projects dealing with the ab-initio calculation
of various materials properties. The topics are ranging from the role
of structural defects on the plastic deformation behavior in steels
and tungsten alloys to fundamental aspects of
martensitic and
massive phase transformations.
We are also dealing with the ab-intio calculation of thermodynamic
properties in the TiAl system and are
investigating the properties of interfaces between various
materials. In the AtoMat project
we develop reliable and efficient computational tools for materials scientists and
engineers to examine and model their systems of interest based on
atomistic approaches towards materials design.
Electronic Excitations. While properties derived from the electronic ground state are well-justified within the framework of density functional theory, the treatment of electronic excitations require a methodology beyond standard DFT. We utilize both, the time-dependent extension of DFT in the linear response regime as well as an approach based on many-body perturbation theory (Bethe-Salpter equation) for the calculation of optical properties. Applications cover absorption spectra of metals, metal and semiconductor surfaces, as well as organic semiconductors and carbon nanostructures with a special focus on excitonic effects on the optical properties for the latter two. Also, the X-ray absorption spectrum (XAS) of various semiconductors and insulators and molecular magnets studied by X-ray magnetic circular dichroism (XMCD) are currently of interest.