A dynamic lattice Monte Carlo model of ion transport in inhomogeneous dielectric environments: Method and implementation
A dynamic lattice Monte Carlo model of ion transport in inhomogeneous dielectric environments: Method and implementation
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DOI：
10.1021/jp001282s
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发表时间：
2000-12-28
影响因子：
3.3
通讯作者：
Coalson, RD
中科院分区：
文献类型：
--
作者：
Graf, P;Nitzan, A;Coalson, RD
提出了一种用于描述介电环境中离子传输的动态晶格蒙特卡罗（DLMC）模拟方法。对于非均匀系统中的非平衡情况，使用周期性边界条件的常规方法效率低下。相反，模拟系统被嵌入一个更大的系统中，该更大系统确定其边界处的平均静电势和离子浓度。有两个问题特别重要：在处理边界处及边界附近的动力学过程时实现给定的边界条件，以及在蒙特卡罗模拟过程中高效评估非均匀介电介质中的离子 - 离子相互作用。通过将数值结果与简单几何形状的精确解以及在后者应能提供合理描述的系统中的平均场（泊松 - 能斯特 - 普朗克，PNP）理论进行比较，来检验该方法的性能。展示并讨论了PNP理论在不同程度上失效的其他例子。特别是，对于离子通过蛋白质和水环境的介电常数差异较大的刚性窄膜通道的传输，PNP结果与DLMC动力学有很大偏差。
A dynamic lattice Monte Carlo (DLMC) simulation approach to the description of ion transport in dielectric environments is presented. Conventional approaches using periodic boundary conditions are inefficient for nonequilibrium situations in inhomogeneous systems. Instead, the simulated system is embedded in a bigger system that determines the average electrostatic potential and the ionic concentrations at its boundaries. Two issues are of special importance: implementing the given boundary conditions in the treatment of dynamical processes at and near the boundaries, and efficient evaluation of ion-ion interaction in the heterogeneous dielectric medium during the Monte Carlo simulation. The performance of the method is checked by comparing numerical results to exact solutions for simple geometries, and to mean field (Poisson-Nernst-Planck, PNP) theory in a system where the latter should provide a reasonable description. Other examples in which the PNP theory fails in various degrees are shown and discussed. In particular, PNP results deviate considerably from the DLMC dynamics for ion transport through rigid narrow membrane channels with large disparity between the dielectric constants of the protein and the water environments.