High-throughput computational search for two-dimensional binary compounds: Energetic stability versus synthesizability of three-dimensional counterparts

TL;DR

This study uses first principles calculations to explore the energetic stability and synthesizability of over a thousand 2D binary compounds across various structures, revealing that negative formation energy alone does not guarantee dynamical stability.

Contribution

It provides a comprehensive high-throughput computational analysis linking energetic stability to synthesizability of 2D binary compounds, challenging previous assumptions.

Findings

Negative formation energy is not sufficient for dynamical stability.

Dynamically stable 2D compounds can be identified through phonon dispersion analysis.

Experimentally synthesized 3D counterparts suggest stability of certain 2D structures.

Abstract

Using first principles calculations, the energetic stability of two-dimensional (2D) binary compounds $XY$ is investigated, where $X$ and $Y$ indicate the metallic element from Li to Pb in the periodic table. Here, 1081 compounds in the buckled honeycomb (BHC), buckled square, B2, L1$_0$, and B$_h$ structures are studied. For the compounds that have negative formation energy in the BHC structure or the compounds that can have the B$_h$ structure, the phonon dispersions of the 2D structures are also calculated. We demonstrate that (i) a negative formation energy is neither a sufficient nor necessary condition for yielding the dynamical stability of 2D compounds; and (ii) if a compound in the B$_h$ structure has been synthesized experimentally, that in the BHC structure is dynamically stable.