In this paper, the electrical and optical properties of single-layer MoS₂ and single-layer WS₂ in three strain states: biaxial tension, biaxial compression, biaxial tension and compression are systematically studied. All calculations are based on the first-principle of density functional theory. The results show that after biaxial tension strain, biaxial compression strain, and biaxial tension-compression strain are applied, the atomic structure, energy band structure, and optical absorption coefficient will show disparate changing trends. When the biaxial tension and compression strain intensity is less than 15%, the bond length, bond angle, and light absorption peak will have little fluctuation with the increase of strain intensity. However, compared with the other two strain states, these two crystal structures are the most volatile at this time. In addition, when 15% biaxial tensile strain is applied, the two crystals can still maintain their kinetic stability.

中文翻译：

---

三种应力状态下单层过渡金属二硫化物的光电性能及稳定性

在本文中，单层MoS ₂和单层WS _{2的电学和光学性质}在三种应变状态下：双轴拉伸、双轴压缩、双轴拉伸和压缩进行了系统的研究。所有计算均基于密度泛函理论的第一原理。结果表明，在施加双轴拉伸应变、双轴压缩应变和双轴拉伸-压缩应变后，原子结构、能带结构和光吸收系数将呈现不同的变化趋势。当双轴拉伸和压缩应变强度小于15%时，键长、键角和光吸收峰随应变强度的增加波动不大。然而，与其他两种应变状态相比，这两种晶体结构此时最不稳定。此外，当施加 15% 双轴拉伸应变时，