Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida, Mérida, Mexico.
Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Santiago, Chile.
J Comput Chem. 2023 Jan 30;44(3):248-255. doi: 10.1002/jcc.26875. Epub 2022 Apr 28.
Herein we show a density functional theory-based study performed on two recently predicted polymorphs of the BeH monolayer, α-BeH and β-BeH . The α-BeH phase possesses an in-plane negative Poisson's ratio (NPR), introducing it into the unique group of auxetic materials. Our assessment delves into the linear-elastic and finite-strain regimes to understand both polymorphs' structural and mechanical responses to deformation. We find that the in-plane NPR is shown to be only parallel to the bonds in α-BeH and remains along the uniaxial tensile path. Concomitantly, an out-of-plane transition toward auxetic is also revealed in regions exhibiting conventional Poisson's ratios, making α-BeH a bidirectionally auxetic material. While phase transitions in β-BeH are triggered at very short strains, α-BeH displays excellent elasticity against tension, superior to that of most currently known 2D materials.
在此，我们展示了基于密度泛函理论对 BeH 单层的两种最近预测的多晶型物——α-BeH 和 β-BeH 进行的研究。α-BeH 相具有面内负泊松比（NPR），使其成为独特的超弹性材料之一。我们的评估深入研究了线弹性和有限应变范围，以了解两种多晶型物在结构和机械变形方面的响应。我们发现，面内 NPR 仅与α-BeH 中的键平行，并沿单轴拉伸路径保持。同时，在表现出常规泊松比的区域中也显示出面外超弹性的转变，使α-BeH 成为一种双向超弹性材料。虽然β-BeH 的相转变是在很短的应变下触发的，但α-BeH 表现出优异的拉伸弹性，优于大多数目前已知的 2D 材料。
