中文摘要：

基于密度泛函理论的平面波赝势方法，运用Castep软件研究了带有不同本征点缺陷的GaAs饱和吸收体的晶格常数和弹性性质，得到了在不同的点缺陷影响下的GaAs晶体的弹性常数，并采用Voigt—Reuss—Hill方法计算得到相应的体积弹性模量B、剪切模量G，并与理想GaAs晶体的弹性模量数值进行对比。本征点缺陷的存在破坏了GaAs晶体的对称性，使晶格发生畸变，晶格常数变小，弹性常数也不再符合立方晶系的弹性常数模式。GaAs饱和吸收体的脆性降低，延性增强，晶格更容易发生切向形变。计算得到的弹性常数将有助于进一步分析含有复杂缺陷结构的GaAs晶体的弹性性质，并对GaAs晶体作为饱和吸收体用于被动调Q激光器具有理论指导意义。

英文摘要：

The lattice constants and elastic properties of GaAs saturable absorber with different intrinsic point defects were studied by the plane-wave pseudopotential method based on density functional theory （DFT） with Cambridge serial total energy package（Castep） program. The elastic constants of GaAs crystal with different intrinsic point defects were obtained. The bulk elastic modulus（B） and the shear modulus（G） were calculated from the theoretical elastic constants by Voigt-Reuss-Hill averaging scheme. The difference of elastic properties between perfect GaAs crystal and defective GaAs crystal was also obtained. The existence of intrinsic point defects destroyed the symmetry of GaAs crystal and made the lattice distortion. Then the lattice constants become smaller. And the elastic constants were not consistent with the elastic constants of cubic crystal＇s model. The intrinsic point defects decreased the brittleness of GaAs and increased the ductility of GaAs, and the lattice was more prone to have a tangential deformation. The values of the elastic constants obtained will be helpful in analyzing the elastic properties of GaAs crystal with complex lattice defects and guiding the application of GaAs crystal as a saturable absorber in passively Q-switched laser.