条带和团块形成体系的结构转变、Melting,和中间相
Structural Transitions, Melting, and Intermediate Phases for Stripe and Clump Forming Systems
摘要：
我们数值研究了一个二维质点系的性质，该系统具有竞争的长程排斥和短程吸引相互作用作为密度和温度的函数。为了增加密度，在低密度团块相、中间条纹相、反团块相和高密度均匀相之间存在明确的过渡。为了表征这些阶段之间的过渡，我们提出了几个措施，考虑到系统中的不同长度尺度。对于增加温度，我们发现一个中间相，是液体状的颗粒间间距的短的长度尺度上，但固体状的较大的长度尺度上的团块，条纹，或anticlump模式。当单个条带内的局部颗粒晶格在远低于整个条带结构破裂的温度下熔化时，该中间相在条带状态下在最宽的温度范围内持续存在，并且其特征在于颗粒的条带内扩散而没有条带间扩散。随后在较高的温度下，在各向异性扩散相中开始条带间扩散，然后条带结构破裂。我们确定这些制度之间的过渡，通过扩散，比热和能量波动测量，并发现内条纹液体制度，过剩熵进入无序的颗粒排列内的条纹，而不是影响条纹结构本身。的团块和anticlump阶段也显示出多个温度诱导的扩散制度，这是不明显的条纹相。
英文摘要：
We numerically examine the properties of a two-dimensional system of particles which have competing long range repulsive and short range attractive interactions as a function of density and temperature. For increasing density, there are well defined transitions between a low density clump phase, an intermediate stripe phase, an anticlump phase, and a high density uniform phase. To characterize the transitions between these phases we propose several measures which take into account the different length scales in the system. For increasing temperature, we find an intermediate phase that is liquid-like on the short length scale of interparticle spacing but solid-like on the larger length scale of the clump, stripe, or anticlump pattern. This intermediate phase persists over the widest temperature range in the stripe state when the local particle lattice within an individual stripe melts well below the temperature at which the entire stripe structure breaks down, and is characterized by intra-stripe diffusion of particles without inter-stripe diffusion. This is followed at higher temperatures by the onset of inter-stripe diffusion in an anisotropic diffusion phase, and then by breakup of the stripe structure. We identify the transitions between these regimes through diffusion, specific heat, and energy fluctuation measurements, and find that within the intra-stripe liquid regime, the excess entropy goes into disordering the particle arrangements within the stripe rather than affecting the stripe structure itself. The clump and anticlump phases also show multiple temperature-induced diffusive regimes which are not as pronounced as those of the stripe phase.
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