We have used molecular dynamics and Monte Carlo methods to simulate the structure and phase stability of a Pd crystal in thermodynamic equilibrium with molecular hydrogen gas at temperature T and pressure PgH2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ P_{g}^{H2} $$\end{document}. The pressure–composition–temperature (PCT) curves were deduced under the extreme conditions of an open system (Pd crystal in equilibrium with a large-volume H2 gas reservoir) and a closed system (Pd crystal in equilibrium with H2 gas reservoir of infinitesimal volume). The PCT curves from the open simulations reproduce the experimental observations, including the ubiquitous hysteresis. The PCT curves from the closed-system simulations are continuous curves. Below a tri-critical point, the Pd–H system decomposes into two coherent phases. We find excellent agreement between the present simulation results and the predictions of the Schwarz–Khachaturyan theory for the decomposition of a Pd–H alloy into two coherent hydride phases.

中文翻译：

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Pd-H 系统中的相干相分解

我们使用分子动力学和蒙特卡罗方法来模拟 Pd 晶体在温度 T 和压力 PgH2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym 与分子氢气的热力学平衡中的结构和相稳定性} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ P_{g}^{H2 } $$\end{文档}。压力-成分-温度 (PCT) 曲线是在开放系统（与大体积 H2 气藏平衡的 Pd 晶体）和封闭系统（与无穷小体积 H2 气藏平衡的 Pd 晶体）的极端条件下推导出来的。 ）。开放式模拟的 PCT 曲线再现了实验观察结果，包括普遍存在的滞后现象。来自封闭系统模拟的 PCT 曲线是连续曲线。在三临界点以下，Pd-H 系统分解为两个相干相。我们发现目前的模拟结果与 Schwarz-Khachaturyan 理论对 Pd-H 合金分解成两个相干氢化物相的预测非常吻合。