Department of Chemistry and Applied Biosciences, ETH Zurich and Facoltà di Informatica, Instituto di Scienze Computazionali, Università della Svizzera italiana, Via Giuseppe Buffi 13, CH-6900 Lugano, Switzerland.
National Center for Computational Design and Discovery of Novel Materials MARVEL, Università della Svizzera italiana, Via Giuseppe Buffi 13, CH-6900 Lugano, Switzerland.
Phys Rev Lett. 2015 Aug 14;115(7):070601. doi: 10.1103/PhysRevLett.115.070601. Epub 2015 Aug 10.
We propose a new method to obtain kinetic properties of infrequent events from molecular dynamics simulation. The procedure employs a recently introduced variational approach [Valsson and Parrinello, Phys. Rev. Lett. 113, 090601 (2014)] to construct a bias potential as a function of several collective variables that is designed to flood the associated free energy surface up to a predefined level. The resulting bias potential effectively accelerates transitions between metastable free energy minima while ensuring bias-free transition states, thus allowing accurate kinetic rates to be obtained. We test the method on a few illustrative systems for which we obtain an order of magnitude improvement in efficiency relative to previous approaches and several orders of magnitude relative to unbiased molecular dynamics. We expect an even larger improvement in more complex systems. This and the ability of the variational approach to deal efficiently with a large number of collective variables will greatly enhance the scope of these calculations. This work is a vindication of the potential that the variational principle has if applied in innovative ways.
我们提出了一种从分子动力学模拟中获取罕见事件动力学性质的新方法。该方法采用了最近提出的变分方法[Valsson 和 Parrinello，Phys. Rev. Lett. 113, 090601 (2014)]来构建一个偏压势，作为几个集体变量的函数，旨在将相关的自由能表面提升到预设的水平。所得到的偏压势有效地加速了亚稳态自由能极小值之间的跃迁，同时确保了无偏跃迁态，从而可以获得准确的动力学速率。我们在几个说明性的系统上测试了该方法，与以前的方法相比，该方法的效率提高了一个数量级，与无偏分子动力学相比，提高了几个数量级。我们预计在更复杂的系统中会有更大的改进。这种方法和变分方法有效地处理大量集体变量的能力将极大地扩展这些计算的范围。这项工作证明了如果以创新的方式应用变分原理，它具有巨大的潜力。
