Crystal Stability Determination of GeSe Allotropes
Zongbao Li, Zeyuan Wu, Mingjie Feng, Xia Wang, Wenbo Lu, Bin Yan, Hui‐Juan Yan, Jin‐Song Hu, Ding‐Jiang Xue
Abstract
Germanium monoselenide (GeSe) has attracted increasing attention recently due to its rich polymorphism including stable room-temperature two-dimensional phases and metastable high-temperature three-dimensional phases that enable GeSe wide applications from optoelectronics to thermoelectrics. However, the relationship between the stability and crystal structure parameters such as bond length and angle is still unclear, where the rough cognition of a shorter covalent bond length is not enough to reveal the stability of crystal structures. Here, we introduce a method to evaluate the stability of five GeSe allotropes through bond and angle distortion metrics based on the stereoactivity of lone pairs existing on the Ge(II) atom. We find that the stereoactivity of lone pairs plays an important role in the bond composition. The stronger stereoactivity of lone pairs is enabled by the larger contribution of Ge 4s and 4p states on bond composition combined with the smaller contribution of Ge 4s to the antibonding orbital at valence band maximum. This thereby results in the stronger bonding strength with more distorted bond angles, finally enhancing the stability of phases.