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arXiv physics/0005073physics.comp-phphysics.chem-ph
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一维稀有事件的有效动态重要性抽样

Efficient Dynamic Importance Sampling of Rare Events in One Dimension

Daniel M. Zuckerman, Thomas B. Woolf

摘要:

利用随机路径积分理论,我们获得了\emph{by simulation}在效率上的实质性收益的计算反应速率在一维,半无限,过阻尼随机系统。使用一个定义良好的衡量效率,我们比较“动态重要性采样”(DIMS)方法的实现无偏模拟。最好的DIMS算法被证明是提高效率的因素约为20的$5 k_B T$势垒高度和300的$9 k_B T$,相比无偏模拟。增益来自于对自然(无偏)、类瞬变交叉事件的密切仿真,其中人为地减少了在速率计算中校正的事件之间的等待时间。使用Onsager-Machlup动作所描述的最可能穿越事件的封闭形式解来生成人工穿越事件。虽然最好的偏置方法需要势的二阶导数(由动作中的“雅可比”项产生,这将在后面详细讨论),但仅使用一阶导数的算法几乎也是如此。我们讨论了一维模型的重要性,更大的系统,并建议扩展到高维系统。

英文摘要:

Exploiting stochastic path integral theory, we obtain \emph{by simulation} substantial gains in efficiency for the computation of reaction rates in one-dimensional, bistable, overdamped stochastic systems. Using a well-defined measure of efficiency, we compare implementations of ``Dynamic Importance Sampling'' (DIMS) methods to unbiased simulation. The best DIMS algorithms are shown to increase efficiency by factors of approximately 20 for a $5 k_B T$ barrier height and 300 for $9 k_B T$, compared to unbiased simulation. The gains result from close emulation of natural (unbiased), instanton-like crossing events with artificially decreased waiting times between events that are corrected for in rate calculations. The artificial crossing events are generated using the closed-form solution to the most probable crossing event described by the Onsager-Machlup action. While the best biasing methods require the second derivative of the potential (resulting from the ``Jacobian'' term in the action, which is discussed at length), algorithms employing solely the first derivative do nearly as well. We discuss the importance of one-dimensional models to larger systems, and suggest extensions to higher-dimensional systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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