We have used molecular dynamics simulations for a comprehensive study of phase separation in a two-dimensional single component off-lattice model where particles interact through the Lennard-Jones potential. Via state-of-the-art methods we have analyzed simulation data on structure, growth and aging for nonequilibrium evolutions in the model. These data were obtained following quenches of well-equilibrated homogeneous configurations, with density close to the critical value, to various temperatures inside the miscibility gap, having vapor-"liquid" as well as vapor-"solid" coexistence. For the vapor-liquid phase separation we observe that $\ell$, the average domain length, grows with time ($t$) as $t^{1/2}$, a behavior that has connection with hydrodynamics. At low enough temperature, a sharp crossover of this time dependence to a much slower, temperature dependent, growth is identified within the time scale of our simulations, implying "solid"-like final state of the high density phase. This crossover is, interestingly, accompanied by strong differences in domain morphology and other structural aspects between the two situations. For aging, we have presented results for the order-parameter autocorrelation function. This quantity exhibits data-collapse with respect to $\ell/\ell_w$, $\ell$ and $\ell_w$ being the average domain lengths at times $t$ and $t_w$ ($\leq t$), respectively, the latter being the age of a system. Corresponding scaling function follows a power-law decay: $~\sim (\ell/\ell_w)^{-λ}$, for $t\gg t_w$. The decay exponent $λ$, for the vapor-liquid case, is accurately estimated via the application of an advanced finite-size scaling method. The obtained value is observed to satisfy a bound.
Coarsening and Aging of Lattice Polymers: Influence of Bond Fluctuations
我们提出的非平衡动力学的崩溃模型灵活的均聚物与固定和波动的单体之间的键简单立方晶格的结果。从我们的蒙特卡罗模拟的结果表明，唯象，在崩溃过程中观察到的事件序列是独立的键标准。虽然在不同温度下的集群（单体）的增长表现出非普适的幂律行为时，债券是固定的，通过考虑对角键的存在下，在债券中引入波动产生的温度无关的增长，这可以描述一个通用的非平衡有限尺寸标度函数与非普适度量因子。我们还研究了相关的老化现象，探测一个合适的两次密度密度自相关函数显示一个简单的幂律缩放相对于不断增长的集群大小。然而，与团簇增长指数$α_c $不同，控制塌缩期间老化的非平衡自相关指数$λ_C$与键类型无关，并且在所有温度下严格遵循我们两人在Phys. Rev. E 93，032506（2016）中提出的界限。
Coarse-Grained Molecular Dynamics Simulations of Oxidative Aging and Stabilization in Polymer Melts with Primary Antioxidants: Effects of Antioxidant Concentration and Molecular Architecture
Nagoya University（名古屋大学）；Arts et Metiers Institute of Technology, CNRS Cnam, HESAM Universite（巴黎国立高等工艺学院，法国国家科学研究中心，Cnam，HESAM大学）
