论文标题

量化问题的低温统计力学:三维Voronoi液体的快速淬火和平衡冷却

Low-temperature statistical mechanics of the QuanTizer problem: fast quenching and equilibrium cooling of the three-dimensional Voronoi Liquid

论文作者

Hain, Tobias M., Klatt, Michael A., Schröder-Turk, Gerd E.

论文摘要

量化问题是镶嵌优化问题,其中确定了点配置,从而使Voronoi细胞最小化了体积分布的第二刻。虽然3D中的基态(最佳状态)几乎可以肯定是以身体为中心的立方晶格,但无序和有效的超均匀状态,其能量非常接近地面状态,这是通过几何劳埃德的算法在进化中稳定的状态而产生的[Klatt等。纳特。 Commun。,10,811(2019)]。当[Ruscher等人在有限温度下被视为有限温度下的统计力学问题时,已将同一系统称为“ Voronoi液体”。 EPL 112,66003(2015)]。在这里,我们研究了Voronoi液体的冷却行为,并具有特殊的视野,以表明有效的超明显状态的稳定性。为了确认Ruscher等人的结果,我们通过分子动力学和蒙特卡洛模拟观察到,在缓慢的准静态平衡冷却时,Voronoi液体从无序的构型中呈现到身体以身体为中心的立方体构型。相比之下,在足够快速的非平衡冷却(不仅在最大速度的极限下),Voronoi液体采用了与Klatt等人确定的有效过度固有的固有结构相似的状态。并防止排序过渡到BCC有序结构。该结果与几何直觉一致,即几何劳埃德的算法对应于一种快速淬火类型。

The Quantizer problem is a tessellation optimisation problem where point configurations are identified such that the Voronoi cells minimise the second moment of the volume distribution. While the ground state (optimal state) in 3D is almost certainly the body-centered cubic lattice, disordered and effectively hyperuniform states with energies very close to the ground state exist that result as stable states in an evolution through the geometric Lloyd's algorithm [Klatt et al. Nat. Commun., 10, 811 (2019)]. When considered as a statistical mechanics problem at finite temperature, the same system has been termed the 'Voronoi Liquid' by [Ruscher et al. EPL 112, 66003 (2015)]. Here we investigate the cooling behaviour of the Voronoi liquid with a particular view to the stability of the effectively hyperuniform disordered state. As a confirmation of the results by Ruscher et al., we observe, by both molecular dynamics and Monte Carlo simulations, that upon slow quasi-static equilibrium cooling, the Voronoi liquid crystallises from a disordered configuration into the body-centered cubic configuration. By contrast, upon sufficiently fast non-equilibrium cooling (and not just in the limit of a maximally fast quench) the Voronoi liquid adopts similar states as the effectively hyperuniform inherent structures identified by Klatt et al. and prevents the ordering transition into a BCC ordered structure. This result is in line with the geometric intuition that the geometric Lloyd's algorithm corresponds to a type of fast quench.

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