A new two-dimensional (2D) material, borophene (2D boron sheet), has been grown successfully recently on single crystal Ag substrates by two parallel experiments [Mannix \textit{et al., Science}, 2015, \textbf{350}, 1513] [Feng \textit{et al., Nature Chemistry}, 2016, \textbf{advance online publication}]. Three main structures have been proposed (β12, χ3 and striped borophene). However, the stability of three structures is still in debate. Using first principles calculations, we examine the dynamical, thermodynamical and mechanical stability of β12, χ3 and striped borophene. Free-standing β12 and χ3 borophene is dynamically, thermodynamically, and mechanically stable, while striped borophene is dynamically and thermodynamically unstable due to high stiffness along a direction. The origin of high stiffness and high instability in striped borophene along a direction can both be attributed to strong directional bonding. This work provides a benchmark for examining the relative stability of different structures of borophene.
@article{arxiv.1608.05877,
title = {Stability and Strength of Atomically Thin Borophene from First Principles Calculations},
author = {Bo Peng and Hao Zhang and Hezhu Shao and Zeyu Ning and Yuanfeng Xu and Hongliang Lu and David Wei Zhang and Heyuan Zhu},
journal= {arXiv preprint arXiv:1608.05877},
year = {2017}
}