Institute for Computational Physics, University of Stuttgart, Stuttgart, Germany.
J Chem Phys. 2013 Apr 28;138(16):164112. doi: 10.1063/1.4801866.
Forward flux sampling (FFS) provides a convenient and efficient way to simulate rare events in equilibrium or non-equilibrium systems. FFS ratchets the system from an initial state to a final state via a series of interfaces in phase space. The efficiency of FFS depends sensitively on the positions of the interfaces. We present two alternative methods for placing interfaces automatically and adaptively in their optimal locations, on-the-fly as an FFS simulation progresses, without prior knowledge or user intervention. These methods allow the FFS simulation to advance efficiently through bottlenecks in phase space by placing more interfaces where the probability of advancement is lower. The methods are demonstrated both for a single-particle test problem and for the crystallization of Yukawa particles. By removing the need for manual interface placement, our methods both facilitate the setting up of FFS simulations and improve their performance, especially for rare events which involve complex trajectories through phase space, with many bottlenecks.
前向通量抽样（FFS）为模拟平衡或非平衡系统中的稀有事件提供了一种便捷、高效的方法。FFS 通过相空间中的一系列界面将系统从初始状态推进到最终状态。FFS 的效率对界面的位置非常敏感。我们提出了两种替代方法，可以在没有先验知识或用户干预的情况下，自动且自适应地在最优位置放置界面，在 FFS 模拟进行时实时进行。这些方法通过在推进概率较低的位置放置更多的界面，使 FFS 模拟能够有效地穿越相空间中的瓶颈。这些方法在单个粒子测试问题和 Yukawa 粒子结晶中都得到了验证。通过消除手动界面放置的需求，我们的方法既方便了 FFS 模拟的设置，又提高了其性能，特别是对于涉及通过相空间的复杂轨迹和多个瓶颈的稀有事件。
