Research Reactor Services Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
J Chem Phys. 2011 Jan 14;134(2):024502. doi: 10.1063/1.3522771.
Density functional theory (DFT) with square gradient approximation for the free energy functional and a model density profile are used to obtain an analytical expression for the size-dependent free energy of formation of a liquid drop from the vapor through the process of homogeneous nucleation, without invoking the approximations used in classical nucleation theory (CNT). The density of the liquid drop in this work is not the same as the bulk liquid density but it corresponds to minimum free energy of formation of the liquid drop. The theory is applied to study the nucleation phenomena from supersaturated vapor of Lennard-Jones fluid. The barrier height predicted by this theory is significantly lower than the same in CNT which is rather high. The density at the center of the small liquid drop as obtained through optimization is less than the bulk density which is in agreement with other earlier works. Also proposed is a sharp interface limit of the proposed DFT of nucleation, which is as simple as CNT but with a modified barrier height and this modified classical nucleation theory, as we call it, is shown to lead to improved results.
密度泛函理论（DFT）采用二次梯度近似自由能泛函和模型密度分布，通过均相成核过程，从气相中获得液滴形成的尺寸相关自由能的解析表达式，而无需采用经典成核理论（CNT）中的近似。在这项工作中，液滴的密度与体相液体密度不同，而是对应于液滴形成的最小自由能。该理论应用于研究 Lennard-Jones 流体过饱和蒸汽的成核现象。该理论预测的势垒高度明显低于 CNT 中的势垒高度，而 CNT 中的势垒高度相当高。通过优化得到的小液滴中心的密度小于体相密度，这与其他早期工作一致。还提出了所提出的成核 DFT 的 sharp interface 极限，它与 CNT 一样简单，但具有修改后的势垒高度，我们称之为修改后的经典成核理论，它被证明可以带来改进的结果。
