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固体塑性实验室时间尺度的分子动力学模拟
Molecular dynamics simulations of plasticity in solids at experimentally relevant timescales
投稿时间:2021-01-17  修订日期:2021-02-26
DOI:
中文关键词:  分子动力学  加速分子动力学  固体塑性  时间尺度
英文关键词:molecular dynamics  accelerated molecular dynamics  plasticity of solid  time scale
基金项目:国家重点研发计划(2017YFB0701502);国家自然科学基金(12072344);中国科学院青年创新促进会 (2017025)
作者单位邮编
王云江 中国科学院力学研究所 100190
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中文摘要:
      随着超级计算机软硬件的飞速提升,基于经验势函数的分子动力学模拟在解析固体塑性的微观机制方面发挥着关键作用。但是,由于传统分子动力学基于牛顿运动方程数值积分,积分时间步长通常为飞秒量级,其模拟的时间尺度通常限于纳秒量级,从而为模拟长时间尺度固体塑性机制带来了巨大的挑战。本文将从分子动力学模拟的时间尺度限制切入,介绍目前国际流行的几种实验室时间尺度原子模拟技术,并以晶体位错塑性与非晶态物质扩散、剪切转变塑性为例,阐述实验室时间尺度、原子精度计算机模拟的思想与实施步骤。最后,我将展望目前加速分子动力学方法普遍存在的问题,并展望可能的解决方案。
英文摘要:
      he molecular dynamics (MD) simulations based on empirical force field has played a critical role in analysis of the microscopic plastic mechanisms of versatile solids, in light of the great advances in both software and hardware of supercomputers. However, the classical MD is conducted by taking time integral of the Newtonian equation of motion with a very tiny timestep of the order of femtosecond. Therefore, a typical MD simulation of million steps only enables to explore a timescale window of nanosecond, which brings about extreme challenge in the long timescale simulations, i.e., experimentally relevant circumstances, of plasticity of solids. This paper will start with a brief introduction of timescale issue in MD. Then, several the state-of-the-art accelerated MD techniques are introduced which are capable of performing atomistic simulations up to experimentally relevant timescales. Several examples—including dislocation plasticity in crystalline metals, as well as diffusion and shear transformation in amorphous materials—will be demonstrated in detail to demonstrate the basic ideas and procedures of atomic-scale simulations at experimental timescale. Finally, I will comment on the common shortage of the modern accelerated molecular dynamics techniques, and remark on the possible solutions for a final goal of MD simulations spanning the whole timescale domain of plasticity in solid.
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