A detailed theoretical investigation to explore the effects of external pressure (0.0GPa, 2.5GPa, 5.0GPa, 7.5GPa, 10GPa, 12.5GPa, 15GPa, 17.5GPa, 20GPa and 25GPa) on structural stability, electronic structure, band gap engineering and its impact on optical properties in LiNbO₃ by using CASTEP code, based on ab-initio density functional theory, with ultra-soft pseudopotential and exchange correlation functional GGA-PBE, is presented. From band structure, it is observed that the top of the valence band is typically controlled by O-2p and Nb-4d orbital electrons and the band gap exhibits nearly linear decreasing trend (3.542eV–2.905eV) with the increasing external pressure. Decreasing trend of the electronic band gap with increase of external pressure is explained with the help of total density of states and elemental partial density of states. Moreover, with the increase of external pressure beyond 25 GPa stability of the structure degrades significantly. In addition, to study the impact of band gap reduction on the optical properties, we have also calculated the refractive index, the reflectivity, absorption function and the energy loss function of the LiNbO₃ by the complex dielectric function under various external pressures. The optical results reveal that the static refractive index increases with the increase of pressure and the variation ranges of the absorption function and the reflectivity rate are also broadened. Absorption spectra, under increase of pressure, show the red shift and the major plasmon peaks display blue shift, which is the thumb proof of electronic band gap reduction. Both the electronic structures and optical properties of LiNbO₃ can be constructively tempered with pressure, which contributes an effective theoretical basis for the further application of the LiNbO₃ under pressure.

详细的理论研究，以探索外部压力（0.0GPa，2.5GPa，5.0GPa，7.5GPa，10GPa，12.5GPa，15GPa，17.5GPa，20GPa和25GPa）对结构稳定性，电子结构，带隙工程及其影响的影响对LiNbO ₃光学性能的影响利用从头算密度泛函理论的CASTEP代码，提出了具有超软伪电位和交换相关泛函的GGA-PBE。从能带结构可以看出，价带的顶部通常受O-2p和Nb-4d轨道电子的控制，并且随着外部压力的增加，带隙呈现出几乎线性的下降趋势（3.542eV–2.905eV）。电子束带隙随外部压力的增加而减小的趋势借助于状态的总密度和状态的元素部分密度来解释。此外，随着外部压力的增加超过25 GPa，结构的稳定性显着降低。此外，为了研究带隙减小对光学性能的影响，我们还计算了折射率，反射率，₃在各种外部压力下具有复杂的介电功能。光学结果表明，静态折射率随压力的增加而增加，吸收函数和反射率的变化范围也变宽。在压力增加的情况下，吸收光谱显示出红移，主要的等离激元峰显示出蓝移，这是电子带隙减小的拇指证据。LiNbO ₃的电子结构和光学性质均可通过压力进行构造性回火，这为在压力下进一步应用LiNbO ₃提供了有效的理论基础。