In the framework of density functional theory (DFT), we investigate the structural deformation, and mechanical behavior of the Janus CrSSe, which has out-of-plane structural asymmetry, with conventional transition metal dichalcogenides (TMDs) CrS${}_2$ and CrSe${}_2$. The Janus CrSSe could be a potential candidate for machinable optoelectronic and piezoelectric applications. We predict that these compounds are chemically, mechanically, and dynamically stable with the covalent bond between the TM(Cr) and chalcogen(X=S, Se) atoms. Due to the influence of tensile strain, the Cr–X bond length of each monolayers increases and the thickness decreases. Interestingly, the in-plane stiffness, shear and layer moduli, Poisson’s ratio, ultimate bi/uni-axial stress of Janus CrSSe are in between the values of CrS${}_2$ and CrSe${}_2$ monolayers. Similar to TMDs, the orientation-dependent in-plane stiffness and Poisson’s ratio demonstrates the isotropic behavior in Janus CrSSe. Furthermore, it can sustain a larger value of uni/bi-axial tensile strain with the critical strain equivalent to CrX${}_2$ monolayers. By applying higher-order strain, we have also found average elastic–plastic behavior as expected. These findings demonstrate that the Janus CrSSe monolayer is a mechanically stable and ductile compound that maintains the hybrid behavior.

在密度泛函理论 (DFT) 的框架内，我们研究了具有面外结构不对称性的 Janus CrSSe 与传统过渡金属二硫属化物 (TMDs) CrS的结构变形和机械行为${}_2$和 CrSe${}_2$. Janus CrSSe 可能是可加工光电和压电应用的潜在候选者。我们预测这些化合物在 TM(Cr) 和硫属元素 (X=S, Se) 原子之间的共价键下在化学、机械和动态方面是稳定的。由于拉伸应变的影响，各单层的Cr-X键长增加，厚度减小。有趣的是，Janus CrSSe 的面内刚度、剪切和层模量、泊松比、极限双轴/单轴应力介于 CrS 的值之间${}_2$和 CrSe${}_2$单层。与 TMD 类似，与方向相关的面内刚度和泊松比证明了 Janus CrSSe 中的各向同性行为。此外，它可以承受更大的单轴/双轴拉伸应变值，临界应变相当于CrX${}_2$单层。通过应用高阶应变，我们还发现了预期的平均弹塑性行为。这些发现表明，Janus CrSSe 单层是一种机械稳定且具有延展性的化合物，可保持混合行为。