Atomic layering at the liquid silicon surface: a first- principles simulation

TL;DR

This study uses first-principles molecular dynamics to reveal atomic layering at the liquid silicon surface, showing layering due to directional bonding without significantly affecting electronic or dynamical properties.

Contribution

First-principles molecular dynamics simulation of liquid silicon surface revealing atomic layering and its origin from directional bonding.

Findings

Pronounced layering observed at the liquid silicon surface.

Layering originates from directional Si-Si bonding.

Layering does not significantly alter electronic or dynamical properties.

Abstract

We simulate the liquid silicon surface with first-principles molecular dynamics in a slab geometry. We find that the atom-density profile presents a pronounced layering, similar to those observed in low-temperature liquid metals like Ga and Hg. The depth-dependent pair correlation function shows that the effect originates from directional bonding of Si atoms at the surface, and propagates into the bulk. The layering has no major effects in the electronic and dynamical properties of the system, that are very similar to those of bulk liquid Si. To our knowledge, this is the first study of a liquid surface by first-principles molecular dynamics.