Dongchul Ihm, Young-Han Shin, Jae-Weon Lee, and Eok-Kyun Lee

Department of Chemistry and School of Molecular Science (BK 21), Korea Advanced Institute of Science and Technology, 373-1, Gusongdong, Yusongku, Taejon, Korea

The relationship between the Kolmogorov-Sinai entropy, $h_{\mathrm{KS}}$, and the self-diffusion coefficient, $D$, is studied for two classical simple fluid systems with purely repulsive potentials (one system with a Wayne-Chandler-Anderson potential and the other with a hard-sphere potential). Numerical simulation data for $h_{\mathrm{KS}}$ and $D$, normalized by the average collision frequency $\nu$ and the diameter of the particle $\sigma$ as natural units of time and distance, reveal that, in the region spanning from normal liquid up to near solidification ($0.50 \le \rho \le 0.93$), the Kolmogorov-Sinai entropy has a power law dependency on the self-diffusion coefficient of the form $h_{\mathrm{KS}}/\nu \propto (D/\sigma^{2}\nu)^{\eta}$, in which $\eta$ is independent of density and temperature.