Three-Dimensional Structure of a Simple Liquid at a Face-Centered-Cubic (001) Solid Surface Interface.

Luyao Bao,Kai Luo,Jun Wen,Haibao Hu,Paavo Sepri

doi:10.1038/srep29786

Luyao Bao, Kai Luo + Show 3 more

Open Access

https://doi.org/10.1038/srep29786

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Abstract

A liquid in the vicinity of a solid-liquid interface (SLI) may exhibit complex structures. In this study, we used molecular dynamics simulations demonstrating for the first time that the liquid adjacent to the SLI can have a two-level structure in some cases: a major structure and a minor structure. Through a time-averaging process of molecular motions, we identified the type of the liquid structure by calculating positions of the maximum liquid density in three spatial dimensions, and these positions were found to distribute in many dispersed zones (called high-density zones (HDZs)). The major structure appears throughout the SLI, while the minor structure only occurs significantly within the third layer. Instead of the previously reported body-centered cubic (BCC) or face-centered-cubic (FCC) types, the major structure was found to show a body-centered tetragonal (BCT) type. The adjacent HDZs are connected by specific junctions, demonstrating that atoms diffuse along some particular high probability paths from one HDZ to another. By considering the three-dimensional liquid density distribution from the continuum point of view, more complete details of the structure and diffusive behavior of liquids in the SLI are also possible to be revealed.

Highlights

In order to better understand phenomena such as wetting, segregation, crystal growth, and perhaps applied topics such as Kapitza resistance and slip[1,2,3,4,5,6,7,8], it is important to investigate issues of fundamental importance at the molecular level
Ρ(y) is considered to be a continuous function, and it represents both the solid-like and liquid-like features of the liquid itself in the solid-liquid interface (SLI). We extended this computational method to three dimensions, so that the time-averaging procedure produced a probabilistic function of the liquid density distribution in space, ρ(x, y, z)
These wall generate low-potential wells (WLPWs) tend to trap liquid atoms and cause them to vibrate around the lowest points of the WLPWs, thereby resulting in the formation of the first liquid layer (FLL)

Summary

Introduction

In order to better understand phenomena such as wetting, segregation, crystal growth, and perhaps applied topics such as Kapitza resistance and slip[1,2,3,4,5,6,7,8], it is important to investigate issues of fundamental importance at the molecular level Some of these issues involve the identification of the structural order type exhibited by a liquid in contact with a flat crystal surface. Some researchers have described the ordering of liquid structures near the interface being similar to that of a pure solid from the atomistic point of view[10] This appears to work for the first few layers, liquid-like features become dominant, as the distance to the interface increases. Such two-dimensional representations may miss important features of liquid structures between adjacent planes

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