Connectivity, dynamics, and structure in a tetrahedral network liquid.
Connectivity, dynamics, and structure in a tetrahedral network liquid.
复制标题
四面体网络液体中的连通性、动力学和结构。
作者：
Sándalo Roldán;L. Rovigatti;F. Sciortino
我们报道了用布朗动力学模拟的方法详细地研究了当温度降低时形成无定形四面体网络的片状粒子液体的结构和动力学。高度定向的粒子相互作用允许我们通过根据每个粒子的键的五模分布将整个粒子集区分为不同的群体来研究系统的连通性。用这种方法，我们展示了粒子键合过程不是随机独立的，但它在低温下表现出明显的键关联。我们进一步探索了系统在真实空间中的动力学，并建立了粒子迁移率和粒子连通性之间的明确关系。特别是，我们提供了低温下反常扩散的证据，并揭示了动力学如何受到弱束缚粒子的短时跳跃运动的影响。最后，我们在傅立叶空间中广泛地研究了系统的动力学和结构，并确定了两个定量相似的长度尺度，一个是动态的，另一个是静态的，它们随着系统的冷却而增加，达到了几个粒子直径量级的距离。我们在定性图中总结了我们的发现，其中粘弹性液体的低温状态是通过粒子的长期亚稳态合作区域的演变网络来理解的。
We report a detailed computational study by Brownian dynamics simulations of the structure and dynamics of a liquid of patchy particles which forms an amorphous tetrahedral network upon decreasing the temperature. The highly directional particle interactions allow us to investigate the system connectivity by discriminating the total set of particles into different populations according to a penta-modal distribution of bonds per particle. With this methodology we show how the particle bonding process is not randomly independent but it manifests clear bond correlations at low temperatures. We further explore the dynamics of the system in real space and establish a clear relation between particle mobility and particle connectivity. In particular, we provide evidence of anomalous diffusion at low temperatures and reveal how the dynamics is affected by the short-time hopping motion of the weakly bounded particles. Finally we widely investigate the dynamics and structure of the system in Fourier space and identify two quantitatively similar length scales, one dynamic and the other static, which increase upon cooling the system and reach distances of the order of few particle diameters. We summarize our findings in a qualitative picture where the low temperature regime of the viscoelastic liquid is understood in terms of an evolving network of long time metastable cooperative domains of particles.