arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1204.0192cond-mat.mtrl-scimath-phmath.MP
收藏

晶体中空位的表征和扩散的一个观测点

An observable for vacancy characterization and diffusion in crystals

Pierre-Antoine Geslin, Giovanni Ciccotti, Eric Vanden-Eijnden, Simone Meloni

摘要:

为了确定空位在晶体中的位置和表征空位的动力学性质,我们提出用量子探针准粒子的基态密度来表示空位,该量子探针准粒子的哈密顿量与样品中原子产生的势能场有关.在本说明书中,动能项的h^2/2 mu系数是一个可调参数,它控制着势能场相关最小值区域中的密度局部化。基于这种描述,我们推导出一组集体变量,我们用在罕见的事件模拟,以确定一些在二维晶体中的空位扩散路径。我们的模拟结果显示,除了简单的和预期的最近邻跳跃路径,集体迁移机制的空缺。这种机制涉及几个晶格位置,并产生长距离迁移的空位。最后,我们还观察到空位诱导的晶体再取向过程。

英文摘要:

To locate the position and characterize the dynamics of a vacancy in a crystal, we propose to represent it by the ground state density of a quantum probe quasi-particle for the Hamiltonian associated to the potential energy field generated by the atoms in the sample. In this description, the h^2/2mu coefficient of the kinetic energy term is a tunable parameter controlling the density localization in the regions of relevant minima of the potential energy field. Based on this description, we derive a set of collective variables that we use in rare event simulations to identify some of the vacancy diffusion paths in a 2D crystal. Our simulations reveal, in addition to the simple and expected nearest neighbor hopping path, a collective migration mechanism of the vacancy. This mechanism involves several lattice sites and produces a long range migration of the vacancy. Finally, we also observed a vacancy induced crystal reorientation process.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑