Strain is a powerful tool to engineer the band structure of bilayer phosphorene.The band gap can be decreased by vertical tensile strain or in-plane compressive strain.At a critical strain,the gap is closed and the bi...Strain is a powerful tool to engineer the band structure of bilayer phosphorene.The band gap can be decreased by vertical tensile strain or in-plane compressive strain.At a critical strain,the gap is closed and the bilayer phosphorene is turn to be a semi-Dirac semimetal material.If the strain is stronger than the criterion,a band-inversion occurs and it re-happens when the strain is larger than another certain value.For the zigzag bilayer phosphorene ribbon,there are two edge band dispersions and each dispersion curve represents two degenerate edge bands.When the first band-inversion happens,one of the edge band dispersion disappears between the band-cross points while the other survives,and the latter will be eliminated between another pair of band-cross points of the second band-inversion.The optical absorption of bilayer phosphorene is highly polarized along armchair direction.When the strain is turn on,the optical absorption edge changes.The absorption rate for armchair polarized light is decreased by gap shrinking,while that for zigzag polarized light increases.The bandtouch and band-inversion respectively result in the sublinear and linear of absorption curve versus light frequency in low frequency limit.展开更多
MoS_(2),a transition metal dichalcogenide(TMDC),has attracted significant amount of attention due to its direct bandgap,tunability and optical properties.Recently,a novel structure consisting of MoS_(2) and noble meta...MoS_(2),a transition metal dichalcogenide(TMDC),has attracted significant amount of attention due to its direct bandgap,tunability and optical properties.Recently,a novel structure consisting of MoS_(2) and noble metal nanoclusters has been reported.Inspired by this,first principle calculations are implemented to predict the structures of M_(6)X_(2) and M_(6)XX'(M=Au,Ag;X,X'=S,Se).The calculated bandgap,band edge position,and optical absorption of these structures prove that the silver compounds(Ag_(6)X_(2) and Ag_(6)XX')have great potential for catalytic water splitting.In addition,biaxial strain(tensile strain and compressive strain)is applied to adjust the properties of these materials.The bandgap presents a quasi-linear trend with the increase of the applied strain.Moreover,the transition between the direct and indirect bandgap is found.The outstanding electronic and optical properties of these materials provide strong evidence for their application in microelectronic devices,photoelectric devices,and photocatalytic materials.展开更多
We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain...We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain model, was included in a complementary manner to lattice relaxation. Density functional theory as well as a hybrid functional method based on a plane wave basis set was employed to calculate the lattice structure, elastic constants, electronic properties and optical properties of perovskite BaZrO3. The lattice parameter c exhibited a clear linear dependence on the imposed in-plane strain, but the Poisson＇s ratio caused by internal relaxation was smaller than the elastic deformation, indicating an ＂inelastic＂ or ＂plastic＂ relaxation manner caused by the introduction of internal relaxation. As a result, the related electronic and optical properties of perovskite BaZrO3 were also strongly affected by the in-plane strain, which revealed an effective way to adjust the properties of perovskite BaZrO3 via internal relaxation.展开更多
Photoelectrochemical water splitting using solar energy,generating oxygen and hydrogen is one of the clean fuel production processes.Inspired by surface-dependent characteristics of Janus structures,a newly designed J...Photoelectrochemical water splitting using solar energy,generating oxygen and hydrogen is one of the clean fuel production processes.Inspired by surface-dependent characteristics of Janus structures,a newly designed Janus monolayer Silicon Phosphorous Arsenide(SiPAs)was analyzed with Density Functional Theory(DFT)methods.Hybrid exchange-correlation functional(HSE06)combined with Wannier90-based analysis for electronic and optical properties of SiPAs reveals that it can act as a photocatalyst.SiPAs show an indirect bandgap of 1.88 eV,absorbing visible light range is 350 to 500 nm.The phonon spectrum confirms dynamic stability.The exciton binding energy is computed with GW/BSE methods.The electronic band edge positions are at-5.75 and-4.43 eV,perfectly straddling the water redox potentials.Interestingly the strain application modifies the bandgap and also non-homogenously widens the absorption band.A novel range of photocatalyst designs with Group IV-V elements with great promise for water-splitting,photovoltaic,and narrow bandgap semiconductor(optoelectronics)applications may be feasible.展开更多
The structural, electronic, and optical absorption properties of TiO2 nanotube （TiO2NT） with Cun clusters （n =1-4） adsorbed on its surface have been investigated based on density functional theory calculations. Th...The structural, electronic, and optical absorption properties of TiO2 nanotube （TiO2NT） with Cun clusters （n =1-4） adsorbed on its surface have been investigated based on density functional theory calculations. The TiO2NT is constructed by rolling up a （101） sheet of anatase TiO2 around the [ 1-01 ] direction; the ground states of Cun/TiOzNT systems are determined by analyzing the average adsorption energies. Calculation results show that odd-even oscillations occur for the average adsorption energy, the Cu-O bond length, and the amount of transferred electrons, with the increase in Cu. cluster size; and the Cun/TiO2NTs with odd n＇s demonstrate stronger interaction between the Cu. cluster and the TiO2NT. Also, the impurity states introduced by the Cun cluster to the band gap of TiOzNT cause an obvious redshift of the optical absorption spectrum toward the visible light region, especially for the even n cases.展开更多
使用多体摄动理论研究了碱土金属氧化物CaO的电子激发态和光吸收谱.运用GW近似方法来改进DFT对电子交换关联的处理,并计算了CaO电子能带结构.考虑到电子与空穴的相互作用,运用二粒子格林函数理论来求解Bethe-Salpeter方程,计算电子-空...使用多体摄动理论研究了碱土金属氧化物CaO的电子激发态和光吸收谱.运用GW近似方法来改进DFT对电子交换关联的处理,并计算了CaO电子能带结构.考虑到电子与空穴的相互作用,运用二粒子格林函数理论来求解Bethe-Salpeter方程,计算电子-空穴激发态,并在此基础上计算光吸收谱.计算结果 CaO能隙为7.0 e V,与实验结果 7.1 e V符合很好;并且CaO光吸收谱的理论结果与实验数据也相符合.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774100 and 11474106)
文摘Strain is a powerful tool to engineer the band structure of bilayer phosphorene.The band gap can be decreased by vertical tensile strain or in-plane compressive strain.At a critical strain,the gap is closed and the bilayer phosphorene is turn to be a semi-Dirac semimetal material.If the strain is stronger than the criterion,a band-inversion occurs and it re-happens when the strain is larger than another certain value.For the zigzag bilayer phosphorene ribbon,there are two edge band dispersions and each dispersion curve represents two degenerate edge bands.When the first band-inversion happens,one of the edge band dispersion disappears between the band-cross points while the other survives,and the latter will be eliminated between another pair of band-cross points of the second band-inversion.The optical absorption of bilayer phosphorene is highly polarized along armchair direction.When the strain is turn on,the optical absorption edge changes.The absorption rate for armchair polarized light is decreased by gap shrinking,while that for zigzag polarized light increases.The bandtouch and band-inversion respectively result in the sublinear and linear of absorption curve versus light frequency in low frequency limit.
基金Projected supported by the National Natural Science Foundation of China(Grant No.11974253)the National Key R&D Program of China(Grant No.2017YFA0303600)Science Specialty Program of Sichuan University(Grant No.2020SCUNL210).
文摘MoS_(2),a transition metal dichalcogenide(TMDC),has attracted significant amount of attention due to its direct bandgap,tunability and optical properties.Recently,a novel structure consisting of MoS_(2) and noble metal nanoclusters has been reported.Inspired by this,first principle calculations are implemented to predict the structures of M_(6)X_(2) and M_(6)XX'(M=Au,Ag;X,X'=S,Se).The calculated bandgap,band edge position,and optical absorption of these structures prove that the silver compounds(Ag_(6)X_(2) and Ag_(6)XX')have great potential for catalytic water splitting.In addition,biaxial strain(tensile strain and compressive strain)is applied to adjust the properties of these materials.The bandgap presents a quasi-linear trend with the increase of the applied strain.Moreover,the transition between the direct and indirect bandgap is found.The outstanding electronic and optical properties of these materials provide strong evidence for their application in microelectronic devices,photoelectric devices,and photocatalytic materials.
基金Funded by the National Natural Science Foundation of China(No.51502179)the Colleges and Universities in Hebei Province Science and Technology Research Project(No.YQ2014033)the Hebei Key Discipline Construction Project(B2012210004 and E2013210038)
文摘We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain model, was included in a complementary manner to lattice relaxation. Density functional theory as well as a hybrid functional method based on a plane wave basis set was employed to calculate the lattice structure, elastic constants, electronic properties and optical properties of perovskite BaZrO3. The lattice parameter c exhibited a clear linear dependence on the imposed in-plane strain, but the Poisson＇s ratio caused by internal relaxation was smaller than the elastic deformation, indicating an ＂inelastic＂ or ＂plastic＂ relaxation manner caused by the introduction of internal relaxation. As a result, the related electronic and optical properties of perovskite BaZrO3 were also strongly affected by the in-plane strain, which revealed an effective way to adjust the properties of perovskite BaZrO3 via internal relaxation.
基金the financial support for conducting part of the computational work,by the Australian Government through the Australian Research Council(ARC)under the centre of Excellence scheme(Project No.CE170100026)National Computational Infrastructure(NCI),a National Facility for computing resources.S K M also acknowledges the computing system resources’support from the University of Tsukuba,Japan through the International Postdoctoral Fellowship of Japan Society for the Promotion of Science(JSPS)’s KAKENHI(Grant No.JP22F32733)+1 种基金during the computational work and finalization of this studyS K M also acknowledges the support of Mr Matta Sai Aneesh,University of Queensland,Australia while preparing the graphical abstract.
文摘Photoelectrochemical water splitting using solar energy,generating oxygen and hydrogen is one of the clean fuel production processes.Inspired by surface-dependent characteristics of Janus structures,a newly designed Janus monolayer Silicon Phosphorous Arsenide(SiPAs)was analyzed with Density Functional Theory(DFT)methods.Hybrid exchange-correlation functional(HSE06)combined with Wannier90-based analysis for electronic and optical properties of SiPAs reveals that it can act as a photocatalyst.SiPAs show an indirect bandgap of 1.88 eV,absorbing visible light range is 350 to 500 nm.The phonon spectrum confirms dynamic stability.The exciton binding energy is computed with GW/BSE methods.The electronic band edge positions are at-5.75 and-4.43 eV,perfectly straddling the water redox potentials.Interestingly the strain application modifies the bandgap and also non-homogenously widens the absorption band.A novel range of photocatalyst designs with Group IV-V elements with great promise for water-splitting,photovoltaic,and narrow bandgap semiconductor(optoelectronics)applications may be feasible.
基金supported by the National Natural Science Foundation of China(Grant No.11104199)the Natural Science Foundation of Shanxi Province,China(Grant No.2012011021-3)
文摘The structural, electronic, and optical absorption properties of TiO2 nanotube （TiO2NT） with Cun clusters （n =1-4） adsorbed on its surface have been investigated based on density functional theory calculations. The TiO2NT is constructed by rolling up a （101） sheet of anatase TiO2 around the [ 1-01 ] direction; the ground states of Cun/TiOzNT systems are determined by analyzing the average adsorption energies. Calculation results show that odd-even oscillations occur for the average adsorption energy, the Cu-O bond length, and the amount of transferred electrons, with the increase in Cu. cluster size; and the Cun/TiO2NTs with odd n＇s demonstrate stronger interaction between the Cu. cluster and the TiO2NT. Also, the impurity states introduced by the Cun cluster to the band gap of TiOzNT cause an obvious redshift of the optical absorption spectrum toward the visible light region, especially for the even n cases.
文摘使用多体摄动理论研究了碱土金属氧化物CaO的电子激发态和光吸收谱.运用GW近似方法来改进DFT对电子交换关联的处理,并计算了CaO电子能带结构.考虑到电子与空穴的相互作用,运用二粒子格林函数理论来求解Bethe-Salpeter方程,计算电子-空穴激发态,并在此基础上计算光吸收谱.计算结果 CaO能隙为7.0 e V,与实验结果 7.1 e V符合很好;并且CaO光吸收谱的理论结果与实验数据也相符合.
