Montero Ana M, Yuste Santos B, Santos Andrés, de Haro Mariano López
Departamento de Física, Universidad de Extremadura, E-06006 Badajoz, Spain.
Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06006 Badajoz, Spain.
Entropy (Basel). 2025 Jan 20;27(1):95. doi: 10.3390/e27010095.
This paper explores how competing interactions in the intermolecular potential of fluids affect their structural transitions. This study employs a versatile potential model with a hard core followed by two constant steps, representing wells or shoulders, analyzed in both one-dimensional (1D) and three-dimensional (3D) systems. Comparing these dimensionalities highlights the effect of confinement on structural transitions. Exact results are derived for 1D systems, while the rational function approximation is used for unconfined 3D fluids. Both scenarios confirm that when the steps are repulsive, the wavelength of the oscillatory decay of the total correlation function evolves with temperature either continuously or discontinuously. In the latter case, a discontinuous oscillation crossover line emerges in the temperature-density plane. For an attractive first step and a repulsive second step, a Fisher-Widom line appears. Although the 1D and 3D results share common features, dimensionality introduces differences: these behaviors occur in distinct temperature ranges, require deeper wells, or become attenuated in 3D. Certain features observed in 1D may vanish in 3D. We conclude that fluids with competing interactions exhibit a rich and intricate pattern of structural transitions, demonstrating the significant influence of dimensionality and interaction features.
本文探讨了流体分子间势中的竞争相互作用如何影响其结构转变。本研究采用了一种通用的势模型，该模型具有一个硬核，随后是两个恒定步长，分别代表阱或肩，在一维（1D）和三维（3D）系统中进行分析。比较这些维度突出了限制对结构转变的影响。推导了一维系统的精确结果，而对于无限制的三维流体则使用有理函数近似。两种情况均证实，当步长为排斥时，总相关函数振荡衰减的波长随温度连续或不连续地演化。在后一种情况下，在温度 - 密度平面中出现一条不连续的振荡交叉线。对于吸引性的第一步和排斥性的第二步，会出现一条费舍尔 - 威多姆线。尽管一维和三维结果具有共同特征，但维度引入了差异：这些行为发生在不同的温度范围内，需要更深的阱，或者在三维中会减弱。在一维中观察到的某些特征在三维中可能会消失。我们得出结论，具有竞争相互作用的流体表现出丰富而复杂的结构转变模式，证明了维度和相互作用特征的重大影响。
