This article describes nonequilibrium techniques for the calculation of free energies of solids using molecular dynamics (MD) simulations. These methods provide an alternative to standard equilibrium thermodynamic integration methods and often present superior efficiency. Here we describe the implementation in the LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) code of two specific nonequilibrium processes that allow the calculation of the free-energy difference between two different system Hamiltonians as well as the free-energy temperature dependence of a given Hamiltonian, respectively. The theory behind the methods is summarized, and we describe (including fragments of LAMMPS scripts) how the process parameters should be selected to obtain the best-possible efficiency in the calculations of free energies using nonequilibrium MD simulations. As an example of the application of the methods we present results related to polymorphic transitions for a classical potential model of iron.
Extending Hamiltonian-Adaptive Resolution Simulation to Interfaces: An Updated LAMMPS Implementation and Application to Porous Solids
Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux（索邦大学，法国国家科学研究中心，界面纳米系统电化学物理化学）；Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459（电化学储能网络（RS2E），FR CNRS 3459）
Linear morphological stability analysis of the solid-liquid interface in rapid solidification of a binary system
在线性近似下，分析了平面固-液界面在小扰动下的界面稳定性。按照Trivedi和Kurz（Trivedi R，Kurz W. Acta Metall 1986;34：1663），其推进了Mullins和Sekerka（Mullins WW，Sekerka RF. J Appl Phys 1964; 35：444）的情况下，快速凝固，我们扩展了该模型，通过引入局部非平衡的溶质扩散场周围的界面。在局部非平衡溶质扩散的存在下，给出了扰动界面周围的热质输运问题的一个解。利用发展中的局部非平衡凝固模型，线性形态稳定性的自洽分析与归因于边缘（中性）和绝对形态稳定的快速移动的界面。特别考虑的情况下，在负和正的温度梯度凝固的界面稳定性。相对于Hoglund和Aziz（Hoglund DE，Aziz MJ. Mat Res Soc Symp Proc 1992;205：325）对Si-Sn合金快速凝固过程中界面破裂的临界溶质浓度的研究。
Hydrogen induced nonmonotonic relaxation in binary mixtures similar to Pd-Er alloys as a transition process in nonequilibrium heterogeneous systems with spinodal decomposition
Fast and accurate quasi-atom method for simultaneous atomistic and continuum simulation of solids
Skolkovo Institute of Science and Technology（斯克尔科沃科学与技术研究所）；Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences B. Gruzinskaya str., 10, bld. 1, Moscow, 123242, Russia（俄罗斯科学院地球物理施密特研究所）；School of Computing and Mathematical Sciences（计算与数学科学学院）；University of Leicester（莱斯特大学）
Hidden correlations in stochastic photoinduced dynamics of a solid-state electrolyte
University of California, Berkeley（加州大学伯克利分校）；The Ohio State University（俄亥俄州立大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；California Institute of Technology（加州理工学院）；Argonne National Laboratory（阿贡国家实验室）
