Study of Statistical Dynamic properties of Strongly Coupled Dusty Plasmas using Molecular Dynamics Simulations

等离子体中的粒子在热平衡状态下通常带负电荷，因为电子的迁移率远高于离子的迁移率。这种带电粒子（即尘埃粒子）通常在自然和人造装置的等离子体中观察到。如果尘埃数密度足够高，且每粒子动能小于粒子间势能，则称为系统处于强耦合状态。在本研究项目中，我们利用分子动力学（MD）模拟研究了等离子体系统在不同耦合条件下的集体运动的动力学性质（如波、扩散、耗散、波动等），以便从统计动力学的角度阐明系统的性质。2001年，我们利用MD模拟计算了汤川系统的动态应力相关函数，并利用Green-Kubo公式计算了该系统在大范围耦合参数下的剪切粘度。由于在强耦合条件下，系统的输运系数在空间和时间上一般是非局域的，因此可以用记忆函数近似地表示这些系数。在2002年，我们使用MD模拟，确定了剪切粘度的记忆函数。特别是如果可以忽略记忆函数对波数的依赖，则系统的宏观行为可以用“广义流体力学方程”来描述。在目前的工作中，我们已经确定了GH方程中出现的系数与汤川系统的热力学参数（如系统温度和粒子间势函数的筛选长度）的依赖关系。利用这些结果，我们现在可以通过求解宏观方程来分析汤川系统在长波和低频极限非平衡条件下的动力学特性

Particulates in plasmas are normally negatively charged in thermal equilibrium since the mobility of electrons is much higher than that of ions. Such charged particulates (I.e., dust particles) are commonly observed in plasmas in both nature and man-made devices. If the dust number density is sufficiently high and the kinetic energy per particle is less than the interparticle potential energy, the system is called to be in strongly coupled state. In this research project, under various coupling conditions, we have investigated dynamical properties (such as waves, diffusion, dissipation, fluctuations, etc.) for collective motions of plasmadust systems, using molecular dynamics (MD) simulations, in order to clarify properties of the system in the light of statistical dynamics. In 2001, we evaluated dynamical stress correlation functions of the Yukawa system, using MD simulations, and calculated shear viscosity of the system in the wide range of coupling parameters, using Green-Kubo formula. Since transport coefficients of the system are generally non-local in space and time under strongly coupled conditions, one may approximately express such coefficients with memory functions. In 2002, using MD simulations, we determined the memory function for shear viscosity. Especially if the dependence of memory function on the wave number can be ignored, the macroscopic behavior of the system can be described by the "generalized hydrodynamics (GH) equations". In the present work, we have determined the dependence of coefficients that appear in the GH equations on the thermodynamical parameters (such as the system temperature and screening length of the interparticle potential function) of the Yukawa system. With these results, we are now able to analyze dynamical properties of the Yukawa system under non-equilibrium conditions in the longwave and lowfrequency limit by solving the macroscopic equations