材料摩擦磨损分子动力学模拟的研究进展

随着新技术的发展以及材料服役环境的日益复杂化,传统的试验研究已经不能满足人们对摩擦磨损的认识需求,因此必须借助数值模拟方法来研究材料的摩擦磨损行为.特别是随着近年来原子尺度理论模型的不断完善和计算机运算能力的不断提高,分子动力学模拟已经成为研究材料摩擦磨损行为和机制的重要方法.本文详细综述了材料摩擦磨损分子动力学模拟的国内外研究现状.首先阐述了分子动力学模拟中势能函数的建立;其次介绍了材料摩擦磨损分子动力学模拟常用的接触模型;然后概述了采用分子动力学模拟方法研究接触面积、载荷、温度、速度和晶体取向等因素对材料摩擦磨损的影响;最后指出了目前材料摩擦磨损分子动力学模拟中存在的一些问题,并对未来发展方向进行了展望.     

分子动力学模拟方法概述

主要介绍分子动力学模拟的基本原理,阐述分子动力学方法的运动方程、数值解法、势函数、边界条件、适用系综以及体系相关性质的计算。最后指出分子动力学模拟方法的优势和发展方向。     

分子动力学模拟及其在表面工程中的应用现状

分子动力学模拟是一种通过经典力学建立分子体系模型,利用数值求解分子体系运动方程,对分子和分子体系结构与性质进行研究的计算机模拟方法。分子动力学作为一种应用非常广泛的分子模拟技术,在物理、化学、生物、材料、医学等各种牵涉到微观世界的学科中,都起到了非常重要的作用。目前,分子动力学已被应用于模拟表面工程中表面涂层的沉积过程及其性质、表面改性过程、薄膜应力状态以及表面裂纹的萌生与扩展等方面。综述了分子动力学模拟技术的发展,介绍了分子动力学的基本原理及算法、原子间势函数的选取以及边界条件的选取,并且综述了分子动力学模拟技术在表面工程中的应用及其进一步的研究方向。     

聚合物共混相容性分子动力学模拟进展

本文简要介绍了分子模拟方法和分子动力学方法.着重从分子动力学模拟角度介绍如何模拟聚合物共混相容性的方法,引入了溶解度参数和Huggins-Flory相互作用参数的概念以及分子动力学模拟的具体方法.文章综述了分子动力学模拟在研究聚合物共混相容性的国内外的现状及应用;并对分子动力学模拟的发展趋势作了展望.     

分子动力学在钢铁冶金中的应用及展望

分子动力学是一种模拟物质结构和性质的方法,概括了分子动力学模拟的基本原理与技术,总结分析了分子动力学在冶金中的应用现状。基于微、介观尺度存在的小尺寸效应,简要介绍了笔者用分子动力学方法在研究钢液中纳米夹杂物的热力学、界面性质等方面的前期工作进展。基于洁净钢技术快速发展的趋势,指出分子动力学在钢铁冶金中将获得广泛应用。     

材料科学中的分子动力学模拟

概述了几种常见条件下分子动力学模拟方法以及边界条件的选取、有关的有限差分技术、势函数的发展、温度和压力控制,介绍了分子动力学模拟技术在吸附性能、薄膜生长以及晶体缺陷等研究方面的成果.     

分子动力学模拟的计算及应用

主要介绍分子动力学模拟的来源,从分子动力学的运动方程出发,详细介绍分子动力学模拟过程中的数据分析方法:有限差分法,分子动力学模拟所适用的系综,以及最后对于模拟数据的热力学性质的计算。     

学术前沿

<正>包装材料中化学物质迁移分子动力学模拟研究进展作者:孙魁魁,王欲翠,蔡金龙,周学成,向红来源:包装学报,2017(2)摘要:概述了分子动力学模拟的基本原理及其应用方法,在此基础上,综述了分子动力学模拟在高阻隔包装材料、缓释包装材料、高性能聚合包装材料中化学物质迁移的研究现状,并提出分子动力学技术在包装材料化学     

碳分子筛膜气体分离机理模拟的研究进展

介绍了近几年来碳分子筛膜气体分离机理研究的状况，包括模拟方法的发展和选择，巳有的非平衡分子动力学方法及目前模拟研究成果。详细地介绍了采用双控容积巨正则分子动力学（DCV-GCMD）方法进行碳分子筛膜气体分离机理模拟的基本原理和实现方法。提出了现有模拟研究所存在的问题及今后发展方向。到目前为止，巳有模拟结果和实验数据还有很好的可比性，通过分析可能的原因并给出了进一步完善模拟的建议。     

分子动力学模拟在冶金熔渣中的应用进展

冶金熔渣是由多种氧化物组成的熔体,常见的有硅酸盐熔渣和铝酸盐熔渣.冶金熔渣具有绝热保温、防止二次氧化、吸收钢液中夹杂物、去除钢液中有害元素等重要作用,制备性能优良的熔渣是实现冶金流程节能减排和绿色发展的重要保证,为此有必要系统地研究冶金熔渣的熔体结构和性质.目前,采用模拟实验直接研究高温熔渣熔体结构和性质的限制因素较多,分子动力学模拟可以弥补实验研究方面的不足.由于冶金熔渣种类繁多、复杂多变,如何在冶金熔渣的微观结构与宏观性质之间建立广泛的关联是当今国内外学者的研究重点.分子动力学模拟可以获得熔渣中不同粒子对的键长、键角、配位数等完整的熔体结构数据.基于此,研究者利用熔体结构的聚合度建立了多组元熔渣黏度与熔体结构单元的定量关系.此外,熔渣的电导率与熔体结构中离子的扩散能力有关,可以通过Nernst-Einstein关系式建立电导率和熔体结构之间的关系.本文综述了分子动力学模拟在冶金熔渣中应用的相关研究.首先,对分子动力学模拟在冶金熔渣中的模拟过程进行了介绍.然后,分别详述了分子动力学模拟技术在硅酸盐熔渣和铝酸盐熔渣中的应用现状.最后,总结了现有的问题,并对分子动力学模拟在冶金熔渣中的应用进行了展望.     

Crystal growth study using combination of molecular dynamics and Monte Carlo methods

Molecular dynamics method although provides details of energies of the system as a function of time, is not suited to simulate the processes involving activation processes. Therefore, we attempted to combine the molecular dynamics and Monte Carlo methods. Using molecular dynamics, the energies of the system were calculated which were subsequently combined with Monte Carlo method using random numbers, epitaxial growth of (111) plane of copper, silver, and gold. While surface adsorption and surface diffusion for copper, silver, and gold were simulated by use of molecular dynamics method, the relation between the growth rate of thin films and the packing density of atoms were obtained using Monte Carlo simulation. Thus, by combining the results of the molecular dynamics method and the Monte Carlo method the growth process of thin films at elevated temperatures were obtained, which is too tedious to be calculated by molecular dynamics alone.     

Tight-binding molecular dynamics for materials simulations

Summary Tight-binding molecular dynamics has recently emerged as a useful method for atomistic simulation of the structural, dynamical and electronic properties of realistic materials. The method incorporates quantum-mechanical calculations into molecular dynamics through an empirical tight-binding Hamiltonian and bridges the gap between ab initio molecular dynamics and simulations using empirical classical potentials. In this paper, we review the accuracy, efficiency, and predictive power of the method and discuss some opportunities and challenges for future development.     

包装材料中化学物质迁移分子动力学模拟研究进展

概述了分子动力学模拟的基本原理及其应用方法,在此基础上,综述了分子动力学模拟在高阻隔包装材料、缓释包装材料、高性能聚合包装材料中化学物质迁移的研究现状,并提出分子动力学技术在包装材料化学物质迁移方面未来的应用方向:深入研究模型处于缺陷状态、复杂环境下的建模方法,不断完善迁移模型库,采用更高性能的计算机来构建更大分子量的模型,以验证和改进模型并提供更多的物性数据,得到一些极限条件或实验无法实现情况下的信息。     

分子动力学模拟在塑料材料中迁移研究现状

目的概述分子动力学模拟方法应用于小分子物质在食品塑料包装材料中迁移研究的应用进展。方法综合近20年国内外分子动力学模拟方法在小分子扩散行为的研究进展。结果采用分子动力学模拟方法不仅可以定性地描述小分子在食品塑料包装材料中的扩散行为,而且能模拟聚合物材料的一些结构与性能,分析影响小分子迁移行为的因素,确定小分子的扩散系数。结论分子动力学模拟方法在食品塑料包装材料迁移研究应用中仍存在许多尚未完善与尚未研究的部分,包括通过分子动力学模拟计算所得扩散系数与实验值、半经验公式计算值有差异,在复合膜中模拟应用较少等方面。     

A combined method of molecular dynamics with micromechanics improved by moving the molecular dynamics region successively in the simulation of elastic--plastic crack propagation

Molecular dynamics is applicable only for a small region of simulation. To simulate a large region it is necessary to combine molecular dynamics with continuum mechanics. Previously we proposed a new model in which molecular dynamics was combined with micromechanics. A molecular dynamics model was applied to the crack tip region and a micromechanics model to the surrounding region. In that model, however, crack propagation simulation must be stopped when the crack tip reaches the boundary of the two regions. In this paper the previous model is improved by moving the molecular dynamics region successively with crack propagation. The improved model may be applied to simulate limitless crack propagation. In order to examine the validity of the improved model, we simulate α-iron. The calculation cost with the improved model is less than a tenth of that of the previous model although the results are equal to each other. The crack tip opening displacement calculated with this model is almost equal to the analytical solution derived by Rice. This revised version was published online in July 2006 with corrections to the Cover Date.     

Feature Activated Molecular Dynamics: Parallelization and Application to Systems with Globally Varying Mechanical Fields

A recently developed hybrid molecular dynamics method (Feature Activated Molecular Dynamics, or FAMD), which was originally designed to extend the scope of certain types of molecular dynamics simulations, is extended here in two ways. First, the method is modified to execute on parallel computer architectures using the MPI communication interface. The parallel FAMD algorithm is demonstrated to be computationally efficient and to substantially increase the length scales accessible with molecular dynamics. The performance of the parallel algorithm is demonstrated using a crystalline system containing 1× 10⁶ atoms, in which 1000 supersaturated self-interstitials are introduced and allowed to aggregate for about 4 ns. In the second part of this paper, the FAMD method is applied to problems in which spatio-temporally varying stress fields are present throughout the simulation cell. In particular, we consider the evolution of a spherical void in a hydrostatically stressed silicon crystal and show that the method can capture the extremely rapid void cavitation dynamics following material failure. Once again, the FAMD approach is demonstrated to provide substantial computational advantages over standard molecular dynamics.     

A method of seamlessly combining a crack tip molecular dynamics enclave with a linear elastic outer domain in simulating elastic–plastic crack advance

Molecular dynamics is applicable only to an extremely small region of simulation. In order to simulate a large region, it is necessary to combine molecular dynamics with continuum mechanics. Therefore, we propose a new model where molecular dynamics is combined with micromechanics. In this model, we apply molecular dynamics to the crack tip region and apply micromechanics to the surrounding region. Serious problems exist at the boundary between the two regions. In this study, we manage to solve these problems, and make possible the simulation of the process of crack propagation at the atomic level. In order to examine the validity of this model, we use α-iron for simulation. If the present model is valid, stress and displacement should vary continuously across the boundary between the molecular dynamics region and the micromechanics region. Our model exhibits just such behavior. This revised version was published online in August 2006 with corrections to the Cover Date.     

基于分子动力学镁合金塑性变形机制的研究进展

基于分子动力学方法的计算材料科学是研究微纳米尺度变形机理的重要途径,有助于理清镁合金不同塑性变形机制间的详细竞争关系。本文概述了镁合金中滑移、孪生和晶界滑移变形机制的作用机理;简要介绍了分子动力学基本原理和适用于密排六方结构金属的常用势函数;详细阐述了基于分子动力学方法镁合金塑性变形机制的研究进展。在综述目前研究存在问题的基础上,指出开发适用于镁合金多元体系的高精度势函数以及如何实现多个尺度的衔接等方面是今后研究的重要方向。     

Lattice dynamics and molecular dynamics simulation of complex materials

In this article we briefly review the lattice dynamics and molecular dynamics simulation techniques, as used for complex ionic and molecular solids, and demonstrate a number of applications through examples of our work. These computational studies, along with experiments, have provided microscopic insight into the structure and dynamics, phase transitions and thermodynamical properties of a variety of materials including fullerene, high temperature superconducting oxides and geological minerals as a function of pressure and temperature. The computational techniques also allow the study of the structures and dynamics associated with disorder, defects, surfaces, interfaces etc.