Understanding the complex physical mechanisms of phase change phenomena such as solidification, evaporation and condensation at the nanoscale depending on the temperature variation in a wide range is very important. This study carried out molecular dynamics simulation to investigate the motion of the argon molecules and their phase changes between the bottom cold and top hot walls whose temperatures cover a wide range of variation from the freezing temperature to the supercritical temperature. The motion of argon molecules and their corresponding final phases of solid, liquid, liquid-gas and supercritical fluid formed in the domain depend on the temperature values at the bottom cold and top hot walls, and were classified into seven different processes. The characteristics of final phases of solid, liquid, liquid-gas and supercritical fluid were analyzed by using the radial distribution function, the surface-averaged temperature distribution along the vertical direction and the volume-averaged temperature in the domain for different phases of argon molecules obtained at the final stage of the non-equilibrium simulation. Furthermore, the time history of the average density of argon molecules at the upper domain has also been reported.

了解相变现象的复杂物理机制非常重要，这取决于纳米范围内的温度变化，例如纳米级的凝固，蒸发和冷凝。这项研究进行了分子动力学模拟，以研究氩分子的运动及其在底部冷壁和顶部热壁之间的相变，这些壁的温度覆盖从冻结温度到超临界温度的宽范围变化。在该区域中形成的氩分子的运动及其相应的固态，液态，液态气体和超临界流体的最终相取决于底部冷壁和顶部热壁的温度值，并分为七个不同的过程。固体，液体，利用径向分布函数，垂直方向上的表面平均温度分布以及在非平衡末期获得的氩分子不同相的区域内的体积平均温度，分析了液态气体和超临界流体模拟。此外，也已报导了上层区域中氩分子平均密度的时程。