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arXiv 1507.01682cond-mat.softcond-mat.stat-mechnlin.PS
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软核粒子冻结形成准晶体和晶体液相

Soft-core particles freezing to form a quasicrystal and a crystal-liquid phase

A. J. Archer, A. M. Rucklidge, E. Knobloch

摘要:

研究了软核粒子通过双尺度势相互作用的系统。潜在的是负责在两个不同的,但可比的长度尺度的液体状态的结构因子的峰值,和一个类似的双峰结构是显而易见的分散关系。动态密度泛函理论在二维被用来确定两个新的状态,该系统,晶体液体状态,其中大多数的粒子位于晶格位置,但少数仍然是免费的,所以像一个液体的行为,和12倍准晶态。两者都存在,即使是深度淬火的液体,并发现在一个政权中,液体是不稳定的调制仅在较小的规模。结果,系统最初朝着小尺度晶体状态演化;然而,该状态不是自由能的最小值,并且因此系统随后尝试重新组织以产生较低能量的较大尺度晶体。这个动力学过程产生具有准晶畴的无序状态,并且甚至在这个大尺度线性稳定时也发生,即,这是一个非线性过程。通过控制初始条件,可以形成完美的准晶。使用布朗动力学模拟的结果证实。

英文摘要:

Systems of soft-core particles interacting via a two-scale potential are studied. The potential is responsible for peaks in the structure factor of the liquid state at two different but comparable length scales, and a similar bimodal structure is evident in the dispersion relation. Dynamical density functional theory in two dimensions is used to identify two novel states of this system, the crystal-liquid state, in which the majority of the particles are located on lattice sites but a minority remains free and so behaves like a liquid, and a 12-fold quasicrystalline state. Both are present even for deeply quenched liquids and are found in a regime in which the liquid is unstable with respect to modulations on the smaller scale only. As a result the system initially evolves towards a small scale crystal state; this state is not a minimum of the free energy, however, and so the system subsequently attempts to reorganize to generate the lower energy larger scale crystals. This dynamical process generates a disordered state with quasicrystalline domains, and takes place even when this large scale is linearly stable, i.e., it is a nonlinear process. With controlled initial conditions a perfect quasicrystal can form. The results are corroborated using Brownian dynamics simulations.

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