SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 6: New Methods: Experiments and Theory
O 6.7: Vortrag
Montag, 27. März 2023, 12:00–12:15, GER 39
Real-time TD-DFTB full periodic implementation for solids and low-dimensional materials — •Carlos R. Lien-Medrano1, Franco P. Bonafé2, Cristián G. Sánchez3, and Thomas Fraeunheim1 — 1University of Bremen, Bremen, Germany — 2MPSD, Hamburg, Germany — 3University of Cuyo, Mendoza, Argentina
The current implementation of the real-time TD-DFTB dynamics for molecules and finite systems in the DFTB+ package[1] is based on the length gauge of the electric field. Here we show a proof-of-concept implementation of the vector potential in the velocity gauge of the electric field that in principle would allow us to extend the real-time dynamics to any periodic direction, making the new implementation suitable for the study of photo-induced dynamics processes in bulk, low-dimensional materials and surfaces. Instead of the dipole moment, the observable of choice is the frequency dependent conductivity which can be obtained from the Fourier transform of the autocorrelation function of the electric current density averaged over a unit cell. The conductivity provides access to the dielectric constant of the system allowing the calculation of optical properties.
[1] Hourahine, B., et al. (2020). DFTB+, a software package for efficient approximate density functional theory based atomistic simulations. The Journal of Chemical Physics, 152(12), 124101.