The relation of interface properties and bulk phase stability: molecular dynamics simulations of carbon dioxide.
The relation of interface properties and bulk phase stability: molecular dynamics simulations of carbon dioxide.
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界面性质与体相稳定性的关系：二氧化碳的分子动力学模拟。
DOI：
10.1021/jp808789p
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
A. R. Imre
中科院分区：
文献类型：
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作者：
T. Kraska;F. Römer;A. R. Imre
通过分子动力学模拟，计算了纯二氧化碳的亚稳态极限，即所谓的spinodal。旋量的测定是基于近年来发展起来的一种基于汽液界面性质的方法。该方法将通过汽液界面的切向压力分量与相图中两相区域的范德华环联系起来。应用热力学稳定性判据，可以确定旋量的位置。以这种方式确定的旋量在这里称为界面旋量。此外，模拟还提供了相图中完全亚稳区域的状态性质方程。比较了密度张量剖面和压力张量剖面的不同相关方程在旋量估计方面的性能。发现界面旋量与热力学平均场旋量在一定的合理偏差范围内是一致的。最后，研究了模拟箱尺寸对旋量特性的影响，表明温度-密度旋量数据与界面厚度无关。使用Lennard-Jones流体的额外模拟在系统尺寸的1.5个数量级范围内证实了这些结果。进一步的结果是，为了获得可靠的结果，界面系统需要很长的模拟时间。
The limit of metastability, the so-called spinodal, is calculated for pure carbon dioxide by molecular dynamics simulation. The determination of the spinodal is based on properties of the liquid vapor interface using a recently developed method. This method relates the tangential pressure component through the vapor-liquid interface to the van der Waals loop in the two-phase region of the phase diagram. By application of the thermodynamic stability criteria, the location of the spinodal can be determined. The spinodal determined in this way is called interface spinodal here. Furthermore, the simulation provides equation of state properties in the complete metastable region of the phase diagram. The performance of different correlation equations for the density and the pressure tensor profiles with respect to the estimation of the spinodal is compared. It has been found that the interface spinodal coincides with the thermodynamic mean field spinodal within some reasonable deviation. Finally the influence of the size of the simulation box on the spinodal properties is investigated showing that the temperature-density spinodal data are independent of the interface thickness. Additional simulations using a Lennard-Jones fluid confirm these results over a range of 1.5 orders of magnitude for the systems size. A further result is that interface systems require a very long simulation time in order to obtain reliable results.