Cooperative Atomic Motion in the Interfacial Dynamics of Strongly Interacting Particle Systems

热激发类弦粒子集体运动是强相互作用粒子系统的普遍性质。最近人们注意到，这种类型的协同运动是不同形式的玻璃形成液体的动力学特征。这种集体原子运动已被发现在最近的分子动力学模拟在大范围的玻璃形成液体的体动力学，它已被直接观察到在测量胶体“硬球”流体。申请人先前的分子动力学模拟已经进一步表明，弦状集体运动在多晶材料的晶界和纳米颗粒的界面中普遍存在。这些一般的热激发的认识提供了一个一般的框架，了解强相互作用粒子系统的灵敏度杂质，压力和几何约束和其他因素，影响原子包装和集体原子运动的规模。强相互作用粒子系统的特殊和可调性质的起源的新观点也提供了一个改进的合理控制其属性的基础上进一步量化和操纵其界面化学和环境的承诺。当前提议的目标是1）将镍纳米颗粒和冰水作为强相互作用的颗粒模型系统，研究和表征镍纳米颗粒烧结和冰预熔期间的协同原子运动，以及2）使用各种类型的扰动（例如，分子和合金添加剂、静水压力、纳米限制），改变协同原子运动，并更好地理解这种集体运动如何影响烧结和预熔的动力学，目的是防止烧结和控制冰的预熔。

Thermally excited collective string-like particle motion is a general property of strongly interacting particle systems. It has recently become noticed that this type of cooperative motion is characteristic of the dynamics of diverse forms of glass forming liquids. Such collective atomic motion has been found in recent molecular dynamics simulations in the bulk dynamics of a wide range of glass forming liquids, and it has been directly observed in measurements on colloidal 'hard sphere' fluids. The applicant's previous molecular dynamics simulations have further indicated that string-like collective motion is prevalent in grain boundaries of polycrystalline materials and interface of nanoparticles. The recognition of the these general thermal excitations provides a general framework for understanding the sensitivity of strongly interacting particle systems to impurities, pressure and geometrical confinement and other factors that affect atomic packing and the scale of collective atomic motion. The new perspective of the origin of the special and tunable properties of strongly interacting particle systems also offers the promise of an improved rational control of their properties based on further quantification and manipulation of their interfacial chemistry and environment. The objectives of current proposal are to 1) taking nickel nanoparticles and ice-water as strongly interacting particle model systems, investigate and characterize cooperative atomic motion during sintering of nickel nanoparticles and premelting of ice, and 2) using various types of perturbations (e.g., molecular and alloy additives, hydrostatic pressure, nanoconfinement), modify the cooperative atomic motion and better understand how such collective motions influence dynamics of sintering and premelting with goals to prevent sintering and to control premelting of ice.