Zhukhovitskii D I
Joint Institute of High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bd. 2, 125412 Moscow, Russia.
J Chem Phys. 2015 Apr 28;142(16):164704. doi: 10.1063/1.4919114.
We explore thermodynamic properties of a vapor in the range of state parameters where the contribution to thermodynamic functions from bound states of atoms (clusters) dominates over the interaction between the components of the vapor in free states. The clusters are assumed to be light and sufficiently "hot" for the number of bonds to be minimized. We use the technique of calculation of the cluster partition function for the cluster with a minimum number of interatomic bonds to calculate the caloric properties (heat capacity and velocity of sound) for an ideal mixture of the lightest clusters. The problem proves to be exactly solvable and resulting formulas are functions solely of the equilibrium constant of the dimer formation. These formulas ensure a satisfactory correlation with the reference data for the vapors of cesium, mercury, and argon up to moderate densities in both the sub- and supercritical regions. For cesium, we extend the model to the densities close to the critical one by inclusion of the clusters of arbitrary size. Knowledge of the cluster composition of the cesium vapor makes it possible to treat nonequilibrium phenomena such as nucleation of the supersaturated vapor, for which the effect of the cluster structural transition is likely to be significant.
我们研究了处于特定状态参数范围内的蒸汽的热力学性质，在此范围内，原子（团簇）束缚态对热力学函数的贡献超过了自由态蒸汽各组分之间的相互作用。假设这些团簇质量轻且足够“热”，以使键的数量最小化。我们使用具有最小原子间键数的团簇的团簇配分函数计算技术，来计算最轻团簇理想混合物的热学性质（热容和声速）。结果表明该问题可精确求解，所得公式仅为二聚体形成平衡常数的函数。这些公式在亚临界和超临界区域直至中等密度下，都能与铯、汞和氩蒸汽的参考数据实现令人满意的关联。对于铯，我们通过纳入任意大小的团簇，将模型扩展到接近临界密度的情况。了解铯蒸汽的团簇组成，有助于处理诸如过饱和蒸汽成核等非平衡现象，而团簇结构转变对这些现象可能具有显著影响。
