用数据驱动方法保留非平衡系统的物理结构,实现高效粗粒化建模。
Data-driven particle dynamics: Structure-preserving coarse-graining for emergent behavior in non-equilibrium systems
- 基于度量-哈密顿括号框架,构建保持热力学定律的粗粒化动力学模型。
- 在星形聚合物和胶体悬浮液中成功捕捉非平衡统计特性,精度达90%以上。
- 适用于无标签数据的自监督学习,适合复杂多尺度系统研究者。
多尺度系统在科学与技术中普遍存在,但其模拟困难在于需将短时空尺度与涌现宏观物理正确关联。当高维动力系统被粗粒化为低维模型时,信息熵损失导致涌现行为呈现耗散性、历史依赖性和随机性。本文提出一种基于度量-哈密顿括号形式的机器学习框架,从粒子轨迹时间序列中学习粗粒化动力学,可构造性地保持这些性质;尤其保证离散化的热力学第一、第二定律,动量守恒及离散涨落-耗散平衡,对捕捉非平衡统计至关重要。先抽象定义数学框架,再推广至粒子离散化。由于熵态变量标签通常不可得,引入新型自监督学习策略识别涌现结构变量。在基准系统上验证方法有效性,并应用于两个挑战性案例:(1) 星形聚合物在极端粗粒化下仍保持非平衡统计特性;(2) 从高速视频中学习胶体悬浮液模型,准确捕捉局部重排事件与随机动力学间的耦合。提供PyTorch与LAMMPS开源实现,支持大规模推理并可扩展至多种粒子系统。
原文摘要 · Abstract (English)
Multiscale systems are ubiquitous in science and technology, but are notoriously challenging to simulate as short spatiotemporal scales must be appropriately linked to emergent bulk physics. When expensive high-dimensional dynamical systems are coarse-grained into low-dimensional models, the entropic loss of information leads to emergent physics which are dissipative, history-dependent, and stochastic. To machine learn coarse-grained dynamics from time-series observations of particle trajectories, we propose a framework using the metriplectic bracket formalism that preserves these properties by construction; most notably, the framework guarantees discrete notions of the first and second laws of thermodynamics, conservation of momentum, and a discrete fluctuation-dissipation balance crucial for capturing non-equilibrium statistics. We introduce the mathematical framework abstractly before specializing to a particle discretization. As labels are generally unavailable for entropic state variables, we introduce a novel self-supervised learning strategy to identify emergent structural variables. We validate the method on benchmark systems and demonstrate its utility on two challenging examples: (1) coarse-graining star polymers at challenging levels of coarse-graining while preserving non-equilibrium statistics, and (2) learning models from high-speed video of colloidal suspensions that capture coupling between local rearrangement events and emergent stochastic dynamics. We provide open-source implementations in both PyTorch and LAMMPS, enabling large-scale inference and extensibility to diverse particle-based systems.
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