8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P1.47Collective dynamics of atoms in liquid Li 70 Bi 30 alloyJean-François Wax, 1 Mark R. Johnson, 2 Livia E. Bove, 3 and Marek Mihalkovic 41 LPMD-UPVM, 1, boulevard Arago, 57078, METZ, France2 Institut Laue Langevin, GRENOBLE, France3 IMPMC - CNRS UMR 7590, PARIS, France4 Slovak Academy of Sciences, BRATISLAVA, SlovakiaThe partial dynamic structure factors of liquid Li 70 -Bi 30 alloy are computed by molecular dynamicssimulations using pair potentials fitted to ab-initio computation in a multi scale approach [1]. Theexistence of fast and slow vibration modes is clearly observed. Their dispersion with q is presented,as well as their behaviour in the hydrodynamic limit (as q decreases). Due to the very high massratio between components, these modes are propagated separately by the light and heavy speciesdown to very low q−vectors. The transition between kinetic (atomic) and hydrodynamic regime isthus observed at very low q. This picture is consistent with Generalized Collective Modes analysisperformed in the case of other mixtures [2]. [1] Wax J. -F. , Johnson M. R. , Bove L. E. andMihalkovic M. Phys. Rev. B 83 144203 (2011) [2] Bryk T. and Wax J. -F. Phys. Rev. B 80 184206(2009)47