arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 0705.3872cond-mat.mtrl-sci
收藏

用从头算分子动力学研究钠液表面和界面的面内结构和有序性

In-plane structure and ordering at liquid sodium surfaces and interfaces from ab initio molecular dynamics

Brent Walker, Nicola Marzari, Carla Molteni

摘要:

已知液态金属表面的原子形成平行于表面的层。我们使用基于密度泛函理论的从头计算分子动力学(MD)模拟方法,分析了液态钠表面层内原子的二维排列。在表面的最近邻分布表明主要是5倍配位,虽然有4倍和6倍配位原子的显着分数。键角分布表明,随着温度向凝固点降低,对应于六重协调的六角排列的原子的角度的移动。我们合理化这些结果与扭曲的六角秩序在表面上,表现出五和六倍协调区域的混合物。液体表面的结果进行比较与经典的MD模拟的液体表面,出现类似的效果,并与从头算MD模拟的模型固-液界面,其中一个显着的转变向六方有序观察到的温度降低。

英文摘要:

Atoms at liquid metal surfaces are known to form layers parallel to the surface. We analyze the two-dimensional arrangement of atoms within such layers at the surface of liquid sodium, using ab initio molecular dynamics (MD) simulations based on density functional theory. Nearest neighbor distributions at the surface indicate mostly 5-fold coordination, though there are noticeable fractions of 4-fold and 6-fold coordinated atoms. Bond angle distributions suggest a movement toward the angles corresponding to a six-fold coordinated hexagonal arrangement of the atoms as the temperature is decreased towards the solidification point. We rationalize these results with a distorted hexagonal order at the surface, showing a mixture of regions of five and six-fold coordination. The liquid surface results are compared with classical MD simulations of the liquid surface, with similar effects appearing, and with ab initio MD simulations for a model solid-liquid interface, where a pronounced shift towards hexagonal ordering is observed as the temperature is lowered.

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。

↑