Wang Zi-Le, Liu Zhirong, Duan Wenhui, Huang Zhi-Feng
Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing 100094, China.
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
Phys Rev E. 2022 Apr;105(4-1):044802. doi: 10.1103/PhysRevE.105.044802.
Effects of three-point direct correlation on properties of the phase field crystal (PFC) modeling are examined for the control of various ordered and disordered phases and their coexistence in both three-dimensional and two-dimensional systems. Such effects are manifested via the corresponding gradient nonlinearity in the PFC free-energy functional that is derived from classical density functional theory. Their significant impacts on the stability regimes of ordered phases, phase diagrams, and elastic properties of the system, as compared to those of the original PFC model, are revealed through systematic analyses and simulations. The nontrivial contribution from three-point direct correlation leads to the variation of the critical point of order-disorder transition to which all the phase boundaries in the temperature-density phase diagram converge. It also enables the variation and control of system elastic constants over a substantial range as needed in modeling different types of materials with the same crystalline structure but different elastic properties. The capability of this PFC approach in modeling both solid and soft matter systems is further demonstrated through the effect of three-point correlation on controlling the vapor-liquid-solid coexistence and transitions for body-centered cubic phase and on achieving the liquid-stripe or liquid-lamellar phase coexistence. All these provide a valuable and efficient method for the study of structural ordering and evolution in various types of material systems.
研究了三点直接关联对相场晶体（PFC）模型性质的影响，以控制三维和二维系统中各种有序和无序相及其共存情况。这种影响通过从经典密度泛函理论导出的PFC自由能泛函中的相应梯度非线性表现出来。通过系统分析和模拟，揭示了与原始PFC模型相比，它们对有序相的稳定区域、相图和系统弹性性质的显著影响。三点直接关联的非平凡贡献导致了有序-无序转变临界点的变化，温度-密度相图中的所有相界都汇聚到该临界点。它还能够根据需要在很大范围内改变和控制系统弹性常数，以便对具有相同晶体结构但弹性性质不同的不同类型材料进行建模。通过三点关联对体心立方相的气-液-固共存和转变的控制以及实现液条纹或液层状相共存的影响，进一步证明了这种PFC方法对固体和软物质系统进行建模的能力。所有这些为研究各种类型材料系统中的结构有序和演化提供了一种有价值且高效的方法。
