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HL: Fachverband Halbleiterphysik

HL 3: Focus Session: Electron-phonon interaction and ultrafast processes in semiconductors

HL 3.4: Vortrag

Montag, 11. März 2013, 10:45–11:00, H13

Ab initio molecular dynamics simulations of ultrafast melting of Si — •Tobias Zier, Eeuwe S. Zijlstra, and Martin E. Garcia — Theoretical Physics, University of Kassel, Germany

After an intense ultrashort-laser excitation of Si the crystalline structure disorders within several 100's of femtoseconds. This phenomenon is known as ultrafast melting. The underlying effect is the bond softening as a consequence of the laser-induced highly nonthermal state in which the electrons have a temperature of several 10 000 K, while the ions remain close to room temperature. Performing MD-Simulations for supercells with up to 640 atoms allowed us to follow the ionic motion after its excitation. Our results provide new insights in the first steps of nonthermal melting by showing that the ionic motion is dominated by different physical effects, dependent on the timescale, namely, acceleration, deceleration, and diffusion.