Nested sampling in the canonical ensemble: Direct calculation of the partition function from NVT trajectories
Nested sampling in the canonical ensemble: Direct calculation of the partition function from NVT trajectories
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DOI：
10.1063/1.4821761
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发表时间：
2013-09-28
影响因子：
4.4
通讯作者：
Nielsen, Steven O.
中科院分区：
文献类型：
--
作者：
Nielsen, Steven O.
嵌套采样作为一种强大的采样技术，可以直接计算实际分子系统的配分函数。然而，它是通过非标准的相空间采样来实现的，这就排除了分子动力学模拟的使用。这里我们展示了如何使用相空间的标准正则（NVT）采样来直接计算配分函数。嵌套NVT抽样过程有两个组成部分。首先，根据直方图重加权策略，从高到低依次选择模拟运行的温度。其次，必要时加入谐波保护伞偏置电位，以增强采样。我们还展示了如何计算一个可观测值的期望值，以及如何计算自由能作为一个序参数的函数。NVT抽样程序在传统的蒙特卡罗和分子动力学代码中是常见的和容易获得的。该算法易于集成到现有代码中，为嵌套采样技术提供了广阔的应用前景。(C) 2013 AIP出版有限责任公司
Nested sampling has emerged as a powerful sampling technique to directly compute the partition function of a realistic molecular system. However, it does so with a non-standard sampling of phase space, which excludes the use of molecular dynamics simulations. Here we show how to use the standard canonical (NVT) sampling of phase space to directly compute the partition function. There are two components to the nested NVT sampling procedure. First, the temperatures at which the simulations should be run are chosen sequentially, from high to low, based on a histogram reweighting strategy. Second, a harmonic umbrella biasing potential is added, where necessary, to enhance the sampling. We also show how to evaluate the expectation value of an observable and compute the free energy as a function of an order parameter. NVT sampling procedures are common and readily available in conventional Monte Carlo and molecular dynamics codes. The proposed algorithm is easy to integrate into existing codes, which opens up the nested sampling technique to a wide audience. (C) 2013 AIP Publishing LLC.