Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 99: Ultrafast Electron Dynamics IV
O 99.10: Vortrag
Freitag, 21. März 2025, 12:45–13:00, H11
Anisotropic electronic response in hexagonal boron nitride to laser excitations from real-time time-dependent density functional theory — •Cheng Wang, Markus E. Gruner, and Rossitza Pentcheva — Department of Physics, University of Duisburg-Essen
Hexagonal boron nitride (h-BN) has a graphite-derived structure where nitrogen (N) and boron (B) atoms occupy alternating sites. In the framework of real-time time-dependent density functional theory (RT-TDDFT), as implemented in the Elk code, we systematically study the response of bulk and single layer h-BN to laser pulses with in- and out-of-plane polarization, different photon energies, duration and fluences. Our analysis focuses on transient charge redistribution and changes in occupation numbers, revealing a marked dependence on both polarization and frequency in bulk and monolayer h-BN. For a photon energy of 4.8 eV, slightly above the DFT band gap, we find a notable charge transfer from N to B pz-orbitals in both bulk and monolayer for in-plane polarization. At 9.5 eV, excitations occur primarily between occupied and unoccupied N px-orbitals with a small charge transfer to B. In the monolayer, these excitations are suppressed for out-of-plane polarization. Finally, we compare our findings for monolayer h-BN with analogous calculations for graphene.
We gratefully acknowledge the funding provided by the DFG through CRC 1242, project C02. We acknowledge computation time at the MagnitUDE and AmplitUDE HPC systems at the University of Duisburg-Essen.
Keywords: Density functional theory; Hexagonal boron nitride