Computer simulation of heterogeneous nucleation of colloidal crystals at planar walls

平面壁上胶体晶体异质成核的计算机模拟

• 批准号: 50807126
• 负责人: Dr. Peter Virnau
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/50807126?language=en
• 关键词: Computer; simulation; heterogeneous; nucleation; colloidal

The classical theory of heterogeneous nucleation at planar walls shall be tested by Monte Carlo simulations for simple models of colloidal suspensions exhibiting a fluid-solid transition. This theory (due to Turnbull) assumes spherecap shaped ”sessile” droplets at the substrate, and the nucleation barrier that appears in the classical theory of homogeneous nucleation is reduced by a factor depending on the Young contact angle. Using the Asakura-Oosawa (AO) model for colloid-polymer mixtures in the range of sizes where the polymers are much smaller than the colloids, and related models, the fluid-crystal interfacial stiffness and free energy for flat interfaces will be extracted from a capillary wave analysis, while free energy barriers of sessile droplets will be estimated by umbrella sampling and other free energy methods. We also address the problem of the line tension. A comparison with density functional calculations, experiments and simulations using complementary approaches or models will be performed, and the results will be useful as input to phase field methods. Later corrugated planar walls shall be considered too.

平面壁上非均相成核的经典理论将通过蒙特卡罗模拟对表现出流固过渡的胶体悬浮液的简单模型进行检验。这个理论（由于特恩布尔）假设基底上有球形的“无根”液滴，并且在均匀成核的经典理论中出现的成核屏障由于一个取决于杨氏接触角的因素而减少。利用Asakura-Oosawa （AO）模型和相关模型，在一定尺寸范围内聚合物比胶体小得多的胶体-聚合物混合物中，从毛细管波分析中提取了液晶界面的刚度和平面界面的自由能，而通过伞形采样和其他自由能方法估计了固定液滴的自由能垒。我们还讨论了线张力的问题。将与密度泛函计算、实验和使用互补方法或模型的模拟进行比较，结果将作为相场方法的输入。以后的波纹平面墙也要考虑。