Parametrizing linear generalized Langevin dynamics from explicit molecular dynamics simulations
Parametrizing linear generalized Langevin dynamics from explicit molecular dynamics simulations
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DOI：
10.1063/1.4922941
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发表时间：
2015-06-28
影响因子：
4.4
通讯作者：
Kuehn, Oliver
中科院分区：
文献类型：
--
作者：
Gottwald, Fabian;Karsten, Sven;Kuehn, Oliver
在原子水平上对多粒子系统的复杂动力学的基本理解是至关重要的。感兴趣的系统通常是宏观尺寸的，但可以划分为几个重要的自由度，这些自由度被最精确地处理，而其他自由度则构成了一个热浴。特别注意在这方面吸引了线性广义朗之万方程，它可以严格推导出的线性投影技术。在这个框架内，与浴的复杂交互可以减少到单个内存内核。该记忆内核又针对所研究的特定系统进行参数化，通常通过基于显式分子动力学数据的时域方法进行。在这里，我们讨论，这个任务是更自然地实现在频域和开发一个基于傅立叶的参数化方法，优于其时域类似物。非常令人惊讶的是，广泛使用的刚性粘结方法在一般情况下是不合适的。重要的是，我们表明，刚性键的方法导致系统的高估的弛豫时间，除非所研究的系统由一个谐波浴双线性耦合到相关的自由度。(C)2015 AIP Publishing LLC.
Fundamental understanding of complex dynamics in many-particle systems on the atomistic level is of utmost importance. Often the systems of interest are of macroscopic size but can be partitioned into a few important degrees of freedom which are treated most accurately and others which constitute a thermal bath. Particular attention in this respect attracts the linear generalized Langevin equation, which can be rigorously derived by means of a linear projection technique. Within this framework, a complicated interaction with the bath can be reduced to a single memory kernel. This memory kernel in turn is parametrized for a particular system studied, usually by means of time-domain methods based on explicit molecular dynamics data. Here, we discuss that this task is more naturally achieved in frequency domain and develop a Fourier-based parametrization method that outperforms its time-domain analogues. Very surprisingly, the widely used rigid bond method turns out to be inappropriate in general. Importantly, we show that the rigid bond approach leads to a systematic overestimation of relaxation times, unless the system under study consists of a harmonic bath bi-linearly coupled to the relevant degrees of freedom. (C) 2015 AIP Publishing LLC.