基于密度泛函理论,采用平面波赝势和BFGS法计算研究了金红石相MgH_2电子结构性质和线性光学性质。基态下,金红石相MgH_2晶体具有良好的弹性力学稳定性,基本结构参数与实验值及其其他理论值符合得较好。Mulliken电荷分布和集居数分析发现...基于密度泛函理论,采用平面波赝势和BFGS法计算研究了金红石相MgH_2电子结构性质和线性光学性质。基态下,金红石相MgH_2晶体具有良好的弹性力学稳定性,基本结构参数与实验值及其其他理论值符合得较好。Mulliken电荷分布和集居数分析发现:金红石相MgH_2晶体中电荷主要从Mg原子向H原子转移,电荷总数主要来源于Mg2p态电子和H1s态电子,金红石相MgH_2属于共价键和离子键混合型化合物。结合电子性质和频率相关介电函数ε(ω)计算研究了金红石相MgH_2的介电函数、线性吸收系数、复折射率及消光系数、反射率和能量损失谱,结果表明:金红石相MgH_2的主要吸收区间位于紫外光区;24.88~42.35 e V能量区间金红石相MgH_2具有很强的透过性;高频情况下,金红石相MgH_2具有极高的反射率。展开更多
采用密度泛函理论中的广义梯度近似平面波超软赝势方法,计算研究了不同浓度Zn原子掺杂纤锌矿结构CdSe的电子与光学性质。结果显示:随着Zn掺杂浓度的升高,纤锌矿Cd1-xZnxSe的体积在减小,形成能降低,掺杂越容易,稳定性变高;Zn掺杂引起导...采用密度泛函理论中的广义梯度近似平面波超软赝势方法,计算研究了不同浓度Zn原子掺杂纤锌矿结构CdSe的电子与光学性质。结果显示:随着Zn掺杂浓度的升高,纤锌矿Cd1-xZnxSe的体积在减小,形成能降低,掺杂越容易,稳定性变高;Zn掺杂引起导带底向高能方向移动,禁带宽度逐渐增加;掺杂后形成的Zn-Se键具有更大的密立根重叠布居数,表现出更强的共价性;体系的直接带隙宽度增加,导致光电子跃迁峰向高能方向发生蓝移;在紫外光区9.75 e V左右,掺杂体系的吸收强度达到最大,能量损失最小。展开更多
The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the deri...The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the derivative of bulk modulus B~ are 3.872/~, 78.2 GPa, and 3.97, respectively. The results are in good agreement with the available experimental and theo- retical values. The electronic structure shows that cubic NaMgF3 is an indirect insulator with a wide forbidden band gap of Eg = 5.90 eV. The contribution of the different bands is analyzed by total and partial density of states curves. Population analysis of NaMgF3 indicates that there is strong ionic bonding in the MgF2 unit, and a mixture of ionic and weak covalent bonding in the NaF unit. Calculations of dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, optical reflectivity, and conductivity are also performed in the energy range 0 to 70 eV.展开更多
The Cu2O and Au-doped Cu2O films are prepared on MgO （001） substrates by pulsed laser deposition. The X-ray photoelectron spectroscopy proves that the films are of Au-doped Cu2O. The optical absorption edge decrease...The Cu2O and Au-doped Cu2O films are prepared on MgO （001） substrates by pulsed laser deposition. The X-ray photoelectron spectroscopy proves that the films are of Au-doped Cu2O. The optical absorption edge decreases by 1.6% after Au doping. The electronic and optical properties of pure and Au-doped cuprite Cu2O films are investigated by the first principles. The calculated results indicate that Cu2O is a direct band-gap semiconductor. The scissors operation of 1.64 eV has been carried out. After correcting, the band gaps for pure and Au doped Cu2O are about 2.17 eV and 2.02 eV, respectively, decreasing by 6.9%. All of the optical spectra are closely related to the dielectric function. The optical spectrum red shift corresponding to the decreasing of the band gap, and the additional absorption, are observed in the visible region for Au doped Cu2O film. The experimental results are generally in agreement with the calculated results. These results indicate that Au doping could become one of the more important factors influencing the photovoltaic activity of Cu2O film.展开更多
The phase transition of gallium phosphide （GAP） from zinc-blende （ZB） to a rocksalt （RS） structure is investigated by the plane-wave pseudopotential density functional theory （DFT）. Lattice constant a0, elasti...The phase transition of gallium phosphide （GAP） from zinc-blende （ZB） to a rocksalt （RS） structure is investigated by the plane-wave pseudopotential density functional theory （DFT）. Lattice constant a0, elastic constants cij, bulk modulus B0 and the pressure derivative of bulk modulus B0 are calculated. The results are in good agreement with numerous experimental and theoretical data. From the usual condition of equal enthalpies, the phase transition from the ZB to the RS structure occurs at 21.9 GPa, which is close to the experimental value of 22.0 GPa. The elastic properties of GaP with the ZB structure in a pressure range from 0 GPa to 21.9 GPa and those of the RS structure in a pressure range of pressures from 21.9 GPa to 40 GPa are obtained. According to the quasi-harmonic Debye model, in which the phononic effects are considered, the normalized volume V/Vo, the Debye temperature 8, the heat capacity Cv and the thermal expansion coefficient a are also discussed in a pressure range from 0 CPa to 40 GPa and a temperature range from 0 K to 1500 K.展开更多
The structural parameters,electronic structure,chemical bonding and optical properties of hexagonal LiIO_(3) are investigated in the framework of density functional theory.The calculated lattice parameters are in agre...The structural parameters,electronic structure,chemical bonding and optical properties of hexagonal LiIO_(3) are investigated in the framework of density functional theory.The calculated lattice parameters are in agreement with the previous experimental work.The band structure,density of states,and Mulliken charge population are obtained,and indicate that hexagonal LiIO_(3) has an indirect band gap of 2.81 eV.Furthermore,the optical properties are also calculated and analyzed in detail.It is shown that hexagonal LiIO_(3) is a promising dielectric material.展开更多
文摘基于密度泛函理论,采用平面波赝势和BFGS法计算研究了金红石相MgH_2电子结构性质和线性光学性质。基态下,金红石相MgH_2晶体具有良好的弹性力学稳定性,基本结构参数与实验值及其其他理论值符合得较好。Mulliken电荷分布和集居数分析发现:金红石相MgH_2晶体中电荷主要从Mg原子向H原子转移,电荷总数主要来源于Mg2p态电子和H1s态电子,金红石相MgH_2属于共价键和离子键混合型化合物。结合电子性质和频率相关介电函数ε(ω)计算研究了金红石相MgH_2的介电函数、线性吸收系数、复折射率及消光系数、反射率和能量损失谱,结果表明:金红石相MgH_2的主要吸收区间位于紫外光区;24.88~42.35 e V能量区间金红石相MgH_2具有很强的透过性;高频情况下,金红石相MgH_2具有极高的反射率。
文摘采用密度泛函理论中的广义梯度近似平面波超软赝势方法,计算研究了不同浓度Zn原子掺杂纤锌矿结构CdSe的电子与光学性质。结果显示:随着Zn掺杂浓度的升高,纤锌矿Cd1-xZnxSe的体积在减小,形成能降低,掺杂越容易,稳定性变高;Zn掺杂引起导带底向高能方向移动,禁带宽度逐渐增加;掺杂后形成的Zn-Se键具有更大的密立根重叠布居数,表现出更强的共价性;体系的直接带隙宽度增加,导致光电子跃迁峰向高能方向发生蓝移;在紫外光区9.75 e V左右,掺杂体系的吸收强度达到最大,能量损失最小。
基金Project supported by the National Natural Science Foundation of China(Grant No.11176020)
文摘The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the derivative of bulk modulus B~ are 3.872/~, 78.2 GPa, and 3.97, respectively. The results are in good agreement with the available experimental and theo- retical values. The electronic structure shows that cubic NaMgF3 is an indirect insulator with a wide forbidden band gap of Eg = 5.90 eV. The contribution of the different bands is analyzed by total and partial density of states curves. Population analysis of NaMgF3 indicates that there is strong ionic bonding in the MgF2 unit, and a mixture of ionic and weak covalent bonding in the NaF unit. Calculations of dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, optical reflectivity, and conductivity are also performed in the energy range 0 to 70 eV.
文摘The Cu2O and Au-doped Cu2O films are prepared on MgO （001） substrates by pulsed laser deposition. The X-ray photoelectron spectroscopy proves that the films are of Au-doped Cu2O. The optical absorption edge decreases by 1.6% after Au doping. The electronic and optical properties of pure and Au-doped cuprite Cu2O films are investigated by the first principles. The calculated results indicate that Cu2O is a direct band-gap semiconductor. The scissors operation of 1.64 eV has been carried out. After correcting, the band gaps for pure and Au doped Cu2O are about 2.17 eV and 2.02 eV, respectively, decreasing by 6.9%. All of the optical spectra are closely related to the dielectric function. The optical spectrum red shift corresponding to the decreasing of the band gap, and the additional absorption, are observed in the visible region for Au doped Cu2O film. The experimental results are generally in agreement with the calculated results. These results indicate that Au doping could become one of the more important factors influencing the photovoltaic activity of Cu2O film.
文摘The phase transition of gallium phosphide （GAP） from zinc-blende （ZB） to a rocksalt （RS） structure is investigated by the plane-wave pseudopotential density functional theory （DFT）. Lattice constant a0, elastic constants cij, bulk modulus B0 and the pressure derivative of bulk modulus B0 are calculated. The results are in good agreement with numerous experimental and theoretical data. From the usual condition of equal enthalpies, the phase transition from the ZB to the RS structure occurs at 21.9 GPa, which is close to the experimental value of 22.0 GPa. The elastic properties of GaP with the ZB structure in a pressure range from 0 GPa to 21.9 GPa and those of the RS structure in a pressure range of pressures from 21.9 GPa to 40 GPa are obtained. According to the quasi-harmonic Debye model, in which the phononic effects are considered, the normalized volume V/Vo, the Debye temperature 8, the heat capacity Cv and the thermal expansion coefficient a are also discussed in a pressure range from 0 CPa to 40 GPa and a temperature range from 0 K to 1500 K.
文摘The structural parameters,electronic structure,chemical bonding and optical properties of hexagonal LiIO_(3) are investigated in the framework of density functional theory.The calculated lattice parameters are in agreement with the previous experimental work.The band structure,density of states,and Mulliken charge population are obtained,and indicate that hexagonal LiIO_(3) has an indirect band gap of 2.81 eV.Furthermore,the optical properties are also calculated and analyzed in detail.It is shown that hexagonal LiIO_(3) is a promising dielectric material.
