Dynamics in dense mixtures: Kinetics versus thermodynamics in non-equilibrium fluctuations, phase separation and structure formation

非平衡弛豫是实验物理和理论物理中的一个重要现象。对于致密的多组分混合物来说尤其如此，这种混合物在自然界中无处不在-在生物流体如细胞质中-以及在软物质中-例如在胶体悬浮液中。已经在平衡时，这种混合物由于分馏而表现出复杂的相行为，其中不同类型的颗粒在相之间不均匀地分配。非平衡过程，如淬火后的相分离，继承了所有的热力学复杂性，但包含动力学效应作为进一步的重要成分。这些动力学效应在连续统方法中由迁移率描述，在稠密系统中具有重要的结构，因为例如不同粒子种类在相反方向上的运动可能比集体粒子运动慢得多或快得多。这可能导致新的现象，如多个时间尺度和长寿命的非平衡结构的出现相分离，这只是刚刚开始探索。本项目将从理论上研究稠密混合物的动力学，以解决这一领域的许多开放性挑战。它的主要新奇在于连接胶体和生物混合物的极限情况下，他们相当不同的热力学，并在研究非平凡的动力学，可以发生在密集，缓慢的混合物。通过这种方式，该项目旨在通过解决一些关键的开放问题，实现我们对稠密混合物物理学的理解的一步变化，同时开发新的方法，例如系统推导迁移率，为未来广泛的工作开辟道路。雄心勃勃的研究计划需要，并明确设计利用，专业知识的独特组合，这两个PI带来的项目。这些方法包括粗粒化技术和非平衡液体的连续方法（M。Krüger）和投影法（P. Sollich）。

Non-equilibrium relaxation is an important phenomenon of fundamental interest in experimental and theoretical physics. This is especially so for dense multi-component mixtures, which are ubiquitous in nature -- in biological fluids such as the cytoplasm -- as well as in soft matter -- for example in colloidal suspensions. Already at equilibrium such mixtures exhibit complex phase behaviour due to fractionation, where particles of different type partition themselves unevenly between phases. Non-equilibrium processes such as phase separation after a quench inherit all of this thermodynamic complexity but contain kinetic effects as a further important ingredient. These kinetic effects, which are described by mobilities in continuum approaches, carry significant structure in dense systems because e.g. movement of different particle species in opposite directions can be much slower or faster than collective particle motion. This can lead to novel phenomena like the emergence of multiple timescales and long-lived non-equilibrium structures in phase separation, which have only begun to be explored.This project will study the dynamics of dense mixtures theoretically to address the many open challenges in this area. Its main novelty lies in connecting the limiting cases of colloidal and biological mixtures with their rather different thermodynamics, and in studying the non-trivial kinetics that can occur in dense, slow mixtures. In this way the project aims to achieve a step change in our understanding of the physics of dense mixtures, by tackling a number of key open questions, while at the same time developing new methodologies for e.g. the systematic derivations of mobilities that will open the way for a broad range of future work. The ambitious research plan requires, and is designed explicitly to exploit, the unique combination of expertise that the two PIs bring to the project. These include coarse-graining techniques and continuum approaches for non-equilibrium liquids (M. Krüger) and projection methods for phase separation in large mixtures (P. Sollich).