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

Fri 911:10-14:00P1.27A new visualization method of transverse wave in liquidsShuji Munejiri, 1 Fuyuki Shimojo, 2 and Kozo Hoshino 11 Hiroshima Univ., 1-7-1, 739-8521, Higashi-Hiroshima, Japan2 Kumamoto Univ, Kumamoto, JapanThe existence of atomic-scale transverse wave in some liquids has been well known since thepioneering work of molecular-dynamics (MD) simulation for collective dynamics of liquid argon[1]. When we investigate properties of atomic-scale transverse wave s by an MD simulation,it is usual to use transverse current correlation function s, which are calculated from a timeseries of atomic coordinates and velocities. Since these functions are, however, defined ina reciprocal space, it is not easy for us to understand how transverse waves are formed byatomic dynamics. Even if we make an animation of atomic dynamics in liquid using dataof atomic positions obtained by an MD simulation, we cannot observe any transverse wavesin the animation because each mode of collective dynamics is covered by thermal motion ofeach atom. In this paper, to extract information of transverse wave from atomic dynamics andexpress it visually, we propose a new method. First we transform a transverse current correlationfunction having one certain wave-vector to a real-space function. Next, using this function wevisualize a relation between atomic motion and transverse waves. We performed ab initio MDsimulations for liquid sodium at 380 K and liquid silicon at 1750 K. The results of transversecurrent correlation functions showed that there exist transverse waves in liquid sodium butthere is no one in liquid silicon. We have shown that our visualization method can successfullydistinguish these two liquid systems in terms of the existence of microscopic transverse waves.Furthermore the visualization gives us a better understanding of atomic dynamics in liquid thanjust the current correlation function does. We discuss how longitudinal and transverse wave interactwith each other in liquid by current correlation functions and also the results of visualization.[1] D. Levesque et al, Phys. Rev. A, 7, 1690 (1973)27