Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 77: Focus Session: Structural Dynamics in Nanoscale Materials Probed by Ultrashort Electron Pulses

O 77.3: Talk

Thursday, March 19, 2015, 11:30–11:45, MA 005

First principles molecular dynamics simulations of nonthermal structural dynamics in nanoscale materials — Tobias Zier, Bernd Bauerhenne, Benjamin Bartocha, Sergej Krylow, Martin E. Garcia, and •Eeuwe S. Zijlstra — Theoretical Physics, FB10, University of Kassel, Germany

Femtosecond-laser pulses create extreme out-of-hermodynamic-equilibrium conditions in matter with electrons that are orders of magnitude hotter than the ions. We simulated the ensuing nonthermal structural dynamics in Si, Ge, Sb, TiO2, and BN-nanotubes with our ab initio Code for Highly excIted Valence Electron Systems (CHIVES) [1], where the laser-excited potential energy surface is computed on the fly. Our simulations allow us to follow materials through exotic types of motion, for example, fractional diffusion in Si [2]. Computed time-resolved structure factors and structure functions provide a direct link to ultrashort electron diffraction experiments.

[1] E. S. Zijlstra, A. Kalitsov, T. Zier, and M. E. Garcia: "Squeezed thermal phonons precurse nonthermal melting of silicon", Phys. Rev. X 3, 011005 (2013).

[2] E. S. Zijlstra, A. Kalitsov, T. Zier, and M. E. Garcia: "Fractional diffusion in silicon", Adv. Mater. 25, 5605 (2013).