Trokhymchuk A, Huerta A, Bryk T
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia.
Facultad de Fisica, Universidad Veracruzana, Xalapa, Mexico.
J Chem Phys. 2025 May 14;162(18). doi: 10.1063/5.0249154.
By combining computer simulations and a unit cell model approach, we study the apparent bimodality of local structural ordering in a system of confined hard disks. It is shown that a two-dimensional (2D) array of hard disks being confined laterally within a quasi-1D hard wall channel of the width commensurate the bulk 2D triangular lattice at disks close packing, possesses a bimodal probability distribution for the distance between the disk's left and right nearest neighbors. The observed feature aligns with the concept of locally favored structures intensively exploited in the studies of anomalous thermodynamic and kinetic behavior of hydrogen-bonding fluids, except that the reported case is driven by entropic bonding only. The bimodality is observed in a range of densities associated with the vicinity of freezing transition in bulk 2D hard disks, indicating a crossover from the "gas-like" to "liquid-like" state in confined quasi-1D hard disks. Such a phenomenon was not reported for bulk 2D hard disks and is physically unexpected for confined q1D hard disks.
通过结合计算机模拟和单胞模型方法，我们研究了受限硬盘系统中局部结构有序性的明显双峰性。结果表明，在宽度与密排时的体二维三角晶格相当的准一维硬壁通道内横向受限的二维硬盘阵列，其磁盘左右最近邻之间的距离具有双峰概率分布。观察到的特征与在氢键流体异常热力学和动力学行为研究中大量使用的局部有利结构概念相符，只是所报道的情况仅由熵键驱动。在与体二维硬盘冻结转变附近相关的一系列密度范围内观察到双峰性，这表明受限准一维硬盘中从“气态”到“液态”状态的转变。这种现象在体二维硬盘中未被报道，并且对于受限的准一维硬盘来说在物理上是出乎意料的。
