Multithermal-multibaric molecular simulations from a variational principle

We present a method for performing multithermal-multibaric molecular dynamics simulations that sample entire regions of the temperature-pressure (TP) phase diagram. The method uses a variational principle [Valsson and Parrinello, Phys. Rev. Lett. 113, 090601 (2014)] in order to construct a bias that leads to a uniform sampling in energy and volume. The intervals of temperature and pressure are taken as inputs and the relevant energy and volume regions are determined on the fly. In this way the method guarantees adequate statistics for the chosen TP region. We show that our multithermal-multibaric simulations can be used to calculate all static physical quantities for all temperatures and pressures in the targeted region of the TP plane. We illustrate our approach by studying the density anomaly of TIP4P/Ice water.

This record includes input and output files, and Jupyter Notebooks describing the analysis of the simulations and the creation of the figures for the paper.

本报告提出一种执行多温-多压分子动力学模拟的方法，该方法能够采样温度-压力（TP）相图中的整个区域。该技术运用变分原理[Valsson 和 Parrinello, 物理评论快报 113, 090601 (2014)]构建偏差，以实现能量和体积的均匀采样。温度和压力的区间被作为输入，相关能量和体积区域随即确定。由此，该方法确保了针对所选TP区域的充分统计性。我们证实，我们的多温-多压模拟可用于计算目标TP平面内所有温度和压力下的所有静态物理量。我们通过研究TIP4P/Ice水的密度异常来阐述我们的方法。该记录包含输入和输出文件，以及描述模拟分析及论文图表制作的Jupyter Notebooks。