Institut für Theoretische Physik, Technische Universität Wien, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria.
J Chem Phys. 2009 Oct 21;131(15):151103. doi: 10.1063/1.3250938.
We present numerical calculations of a four-point dynamic susceptibility, chi(4)(t), for the Kob-Andersen Lennard-Jones mixture as a function of temperature T and density rho. Over a relevant range of T and rho, the full t-dependence of chi(4)(t) and thus the maximum in chi(4)(t), which is proportional to the dynamic correlation volume, are invariant for state points for which the scaling variable rho(gamma)/T is constant. The value of the material constant gamma is the same as that which superposes the relaxation time tau of the system versus rho(gamma)/T. Thus, the dynamic correlation volume is a unique function of tau for any thermodynamic condition in the regime where density scaling holds. Finally, we examine the conditions under which the density scaling properties are related to the existence of strong correlations between pressure and energy fluctuations.
我们呈现了四点动态磁化率 χ(4)(t) 的数值计算结果，该结果是作为温度 T 和密度 ρ 的函数给出的，用于 Kob-Andersen Lennard-Jones 混合物。在 T 和 ρ 的相关范围内，χ(4)(t) 的完整 t 依赖性，以及与动态相关体积成正比的 χ(4)(t) 的最大值，对于缩放变量 ρ(γ)/T 为常数的状态点是不变的。材料常数 γ 的值与系统的弛豫时间 τ 相对于 ρ(γ)/T 的叠加相同。因此，在密度标度成立的范围内的任何热力学条件下，动态相关体积都是 τ 的唯一函数。最后，我们研究了密度标度性质与压力和能量涨落之间存在强相关性之间的关系的条件。
