【摘要】 将电荷间的库仑作用能分解为实空间作用能、倒空间作用能和自能三部分 ,用静电学原理和傅立叶变换方法推导了三种能量的计算公式 ,得到了与Ewald求和公式一致的结果 .研究结果成功地应用于电中性离子体系的蒙特卡罗计算机分子模拟 ,讨论了实空间截断距离、收敛参数、波矢数量对模拟时间和计算精度的影响 ,得到了相应的优化参数 .更多还原

【Abstract】 Molecular simulation is a powerful tool in studying properties of complex fluids composed of charged particles such as electrolyte solutions, room temperature ionic liquids and colloid solutions, where the long-range interactions play a determinative role. Several methods have been available for treating the long-range interactions between charged particles and point dipole. These include the Ewald sum (ES), the reaction field and particle-particle particle-mesh methods. Among these approaches, the ES is most commonly used. However, several ES versions have been occurred in the literatures of molecular simulation, and sometimes it is difficult for one to choose the right formula to use in molecular simulation study. The coulombic interaction energy between charged particles is divided into the sum of real space, reciprocal space and self energy, and their calculation equations are obtained respectively using electrostatics theory and Fourier transformation method. The Ewald sum formulae have been derived and the clear physical picture involved has been depicted. A Monte Carlo computer simulation for electrostatic interaction energy of charged hard sphere system has been conducted at varying conditions, and a good agreement with MSA is obtained. On this basis the effects on the simulation accuracy and efficiency of real space cut distance r cut, convergence parameter κ and reciprocal maximum vector K max have been analyzed. From the theoretical and computer simulation presented here, the optimization parameters for r cut, κ and K max are obtained as 0.5L(i.e. half box length), 5.8 and 3～5, respectively.更多还原