Molecular Models Applied to the Heterogeneous Nucleation of Ice: Ice Formation on Surfaces

芭芭拉·黑尔教授将应用水/冰系统的计算机模型和比例成核速率形式化来研究非均相冰的成核。目的是从微观底物性质的角度来描述自然大气冰核和人工冰核的成核特征，发展提供微观底物性质的分析方法，发展提供方便估计临界温度和非均相成核速率的分析方法。具体来说，在模型底物（如模型碘化银基面和模型羟基化二氧化硅表面）和具有改性水的底物上吸附水层结冰的阈值温度。衬底相互作用将被检查的影响：(1)衬底晶格结构，(2)水。衬底结合能，(3)衬底边缘缺陷，(4)外电场和压力脉冲扰动，(5)凝结水层厚度。计算机模拟使用有效的水。水和水。利用底物原子对势和蒙特卡罗技术生成吸附水/冰系统热力学量的典型系综平均。这项工作很重要，因为它提供了非均相相变机制的定量描述，特别是冰相的形成。

Professor Barbara Hale will apply computer models of water/ice systems and a scaled nucleation rate formalism to the study of heterogeneous ice nucleation. The goals are to characterize ice nucleating features of natural atmospheric and artificial ice nuclei in terms of microscopic substrate properties and develop analytic the which provide microscopic substrate properties and develop analytic the which provide convenient estimates of threshold temperatures and heterogeneous nucleation rates. Specifically, threshold temperatures for ice formation in adsorbed water layers on model substrates (such as a model silver iodide basal face and a model hydroxylated silica surface) and on substrates with modified water.substrate interactions will be examined for effects of: (1) substrate lattice structure, (2) water.substrate binding energy, (3) substrate ledge defects, (4) external electric field and pressure pulse perturbations, and (5) thickness of the condensed water layers. The computer simulations use effective water.water and water.substrate atomic pair potentials and Monte Carlo techniques to generate canonical ensemble averages of thermodynamic quantities for the adsorbed water/ice systems. This work is important because it provides quantitative descriptions of the heterogeneous phase change mechanism, in particular, the ice phase formation.