Williams Ian, Oğuz Erdal C, Jack Robert L, Bartlett Paul, Löwen Hartmut, Royall C Patrick
H.H. Wills Physics Laboratory, Tyndall Ave., Bristol BS8 1TL, United Kingdom.
Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
J Chem Phys. 2014 Mar 14;140(10):104907. doi: 10.1063/1.4867785.
The behaviour of materials under spatial confinement is sensitively dependent on the nature of the confining boundaries. In two dimensions, confinement within a hard circular boundary inhibits the hexagonal ordering observed in bulk systems at high density. Using colloidal experiments and Monte Carlo simulations, we investigate two model systems of quasi hard discs under circularly symmetric confinement. The first system employs an adaptive circular boundary, defined experimentally using holographic optical tweezers. We show that deformation of this boundary allows, and indeed is required for, hexagonal ordering in the confined system. The second system employs a circularly symmetric optical potential to confine particles without a physical boundary. We show that, in the absence of a curved wall, near perfect hexagonal ordering is possible. We propose that the degree to which hexagonal ordering is suppressed by a curved boundary is determined by the "strictness" of that wall.
材料在空间受限条件下的行为敏感地依赖于限制边界的性质。在二维情况下，硬圆形边界内的受限会抑制在高密度体系统中观察到的六边形有序排列。通过胶体实验和蒙特卡洛模拟，我们研究了圆对称受限条件下的两种准硬圆盘模型系统。第一个系统采用自适应圆形边界，通过全息光镊实验定义。我们表明，该边界的变形允许并实际上是受限系统中六边形有序排列所必需的。第二个系统采用圆对称光势来限制粒子而无物理边界。我们表明，在没有弯曲壁的情况下，近乎完美的六边形有序排列是可能的。我们提出，弯曲边界抑制六边形有序排列的程度由该壁的“严格程度”决定。
