化学燃料分子马达的非平衡分子动力学模拟
Simulating a Chemically-Fueled Molecular Motor with Nonequilibrium Molecular Dynamics
摘要：
大多数分子动力学的计算机模拟都是在平衡条件下进行的--在一个封闭的、孤立系中，或者在一个保持恒定温度或压力的系统中。有时候，在这些模拟中引入额外的张力、剪切力或温度梯度，以探测对外力的一种非平衡响应。然而，催化剂和分子马达的功能是基于化学反应的热力学驱动力引起的非平衡动力学。在这种情况下，模拟需要恒化器能够保持非平衡稳态的化学浓度。我们开发了这样一个动态的计划，并用它来观察一个新的基于粒子的经典模型的链状分子马达周期。分子马达经常用详细的平衡破坏马尔可夫模型来建模，我们通过对模拟的微观动力学进行粗粒化来明确地构建这样一幅图，以提取速率。这项工作确定了粒子间的相互作用，调整这些速率，以创建一个功能的电机，从而产生一个计算的操场，以调查方向偏差，电流生成和耦合强度之间的相互作用，在分子信息棘轮。
英文摘要：
Most computer simulations of molecular dynamics take place under equilibrium conditions--in a closed, isolated system, or perhaps one held at constant temperature or pressure. Sometimes, extra tensions, shears, or temperature gradients are introduced to those simulations to probe one type of nonequilibrium response to external forces. Catalysts and molecular motors, however, function based on the nonequilibrium dynamics induced by a chemical reaction's thermodynamic driving force. In this scenario, simulations require chemostats capable of preserving the chemical concentrations of the nonequilibrium steady state. We develop such a dynamic scheme and use it to observe cycles of a new particle-based classical model of a catenane-like molecular motor. Molecular motors are frequently modeled with detailed-balance-breaking Markov models, and we explicitly construct such a picture by coarse graining the microscopic dynamics of our simulations in order to extract rates. This work identifies inter-particle interactions that tune those rates to create a functional motor, thereby yielding a computational playground to investigate the interplay between directional bias, current generation, and coupling strength in molecular information ratchets.
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