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arXiv 2510.04546cond-mat.softcond-mat.stat-mech
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强受限流体的平衡性质

Equilibrium properties of strongly confined fluids

Ana M. Montero

AI总结:

本研究聚焦极窄通道中单列排布的强受限流体,提出基于映射方法的理论框架将其转化为等效一维混合物,推导热力学与结构量表达式,经模拟验证揭示了维度效应和各向异性相关的新现象。

摘要:

从粒子间相互作用势的认知出发,对流体平衡性质开展统计力学研究,对于理解单个粒子间的微观相互作用在流体性质中发挥的作用至关重要。因此,从基础层面研究这些性质是凝聚态物理的核心目标。然而,当流体被限制在极窄的通道中时,这些性质可能会发生极大变化,故而必须单独开展研究。本论文探究了窄孔隙中的流体,此类环境下粒子被迫以单列形式排布且无法相互穿越。由此形成的系统具有高度各向异性:粒子沿通道轴的运动是自由的,但横向运动受到强烈限制。为量化这些效应,我们将受限流体的平衡性质与体相流体的对应性质进行了对比,揭示了维度的作用。我们还提出了一种基于映射方法的新型理论框架,该框架可将具有最近邻相互作用的单列流体转化为等效的一维混合物。这种精确同构关系给出了热力学量和结构量的闭合表达式,使我们能够计算各向异性压力张量,并修正了空间关联的定义以纳入空间各向异性的影响。该理论被应用于硬球模型、方阱模型、方肩模型以及各向异性硬体模型,揭示了诸如锯齿形有序化和空间关联的结构转变等现象。我们通过蒙特卡罗模拟和分子动力学模拟(包括原创模拟和文献中的模拟结果)对解析预测进行了广泛验证,结果表明在研究的参数范围内二者吻合度极高。

英文摘要:

The statistical-mechanical study of the equilibrium properties of fluids, starting from the knowledge of the interparticle interaction potential, is essential to understand the role that microscopic interaction between individual particles play in the properties of the fluid. The study of these properties from a fundamental point of view is therefore a central goal in condensed matter physics. These properties, however, might vary greatly when a fluid is confined to extremely narrow channels and, therefore, must be examined separately. This thesis investigates fluids in narrow pores, where particles are forced to stay in single-file formation and cannot pass one another. The resulting systems are highly anisotropic: motion is free along the channel axis but strongly restricted transversely. To quantify these effects, equilibrium properties of the confined fluids are compared with their bulk counterparts, exposing the role of dimensionality. We also develop a novel theoretical framework based on a mapping approach that converts single-file fluids with nearest-neighbor interactions into an equivalent one-dimensional mixture. This exact isomorphism delivers closed expressions for thermodynamic and structural quantities. It allows us to compute the anisotropic pressure tensor and revises definitions of spatial correlations to take into account spatial anisotropy. The theory is applied to hard-core, square-well, square-shoulder, and anisotropic hard-body models, revealing phenomena such as zigzag ordering and structural crossovers of spatial correlations. Analytical predictions are extensively validated against Monte Carlo and molecular dynamic simulations (both original and from the literature), showing excellent agreement across the studied parameter ranges.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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