# Our research group

Our group is working in the field of computational materials science and has a large experience in using density functional (DFT) based methods in solids and nanostructures.

Inherent problems of standard DFT necessitates to employ post-DFT methods as well. The advent of almost ubiquitous high-performance computing (HPC) and turnkey program packages allowed to go beyond regular DFT calculations. In the hybrid density functional approach the Hartree-Fock exchange functional is mixed into a selected density functional (typically, PBE GGA). The calculational capacity and time needed for hybrid calculations, usually an order of magnitude larger than for common DFT-based calculations, but still doable for large number of atoms. While the mixing parameter is usually fitted to empirical data, its predictive power is superior over traditional DFT methods, regarding the electronic band gaps or internal excitation energies. Its one of the most important advantages over the parameter-free many body perturbation theory methods, like GW-method, is that the forces can be calculated analytically. Thus the geometry optimization is straightforward for many-atom systems. In our experience, the GW-method produces very similar quasi-particle levels as our well-chosen hybrid functional.

The group started to apply advanced density functional theory methods on defects in bulk and nanostructured semiconductors already from 2002. The first results published in 2003 with using hybrid functional. From 2005 the GW method was also applied. Advanced time-dependent DFT (TDDFT) has been employed to determine the absorption spectrum of nanoclusters since 2008. These theories were utilized directly to defect engineering in bulk semiconductors and in their oxide interface, spintronics, solar cells, biomarkers, and more.

## Group members

- Group leader
- Adam Gali
- Postdoc fellows
- Zoltán Bodrog
- Dávid Beke
- Viktor Ivády
- Bálint Somogyi
- Emilie Bruyer
- Graduate students
- Gyula Károlyházy
- Gergő Thiering
- Péter Udvarhelyi
- András Csóré
- Undergraduate students
- Áron Dániel Major
- Fanni Oláh
- Balázs Juhász
- Dániel Unyi
- Ádám Pataki
- Laboratory Assistants
- Péter Rózsa
- István Balogh
- Dávid Veres