In order to clarify the mechanism of optical transitions for cubic SrHfO_3, we have investigated the electronicstructure and optical properties of cubic SrHfO_3 using the plane-wave ultrasoft pseudopotential technique...In order to clarify the mechanism of optical transitions for cubic SrHfO_3, we have investigated the electronicstructure and optical properties of cubic SrHfO_3 using the plane-wave ultrasoft pseudopotential technique based on thefirst-principles density-functional theory (DFT).The ground-state properties, obtained by minimizing the total energy,are in favorable agreement with the previous work.From the band structure and charge densities as well as the theoryof crystal-field and molecular-orbital bonding, we have systematically studied how the optical transitions are affected bythe electronic structure and molecular orbitals.Our calculated complex dielectric function is in good agreement withthe experimental data and the optical transitions are in accord with the electronic structure.展开更多
1 Introduction Since its first discovery in 1992, ordered mesoporous silica material with large pore size, high surface area, and high pore volume has attracted great attention for the potentially wide application in...1 Introduction Since its first discovery in 1992, ordered mesoporous silica material with large pore size, high surface area, and high pore volume has attracted great attention for the potentially wide application in catalysis, adsorption, separation, and ion exchange, etc. However, the poor hydrothermal stability of mesoporous silica has limited its wide application in industry. Therefore, in the last 10 years, many studies have been dedicated to improving the hydrothermal stability of mesoporous silica. Xiao et al.展开更多
Electronic, chemicM bonding and optical properties of cubic Hf3N4 （ c-Hf3N4 ） are calculated using the first- principles based on the density functional theory （DFT）. The optimized lattice parameter is in good agr...Electronic, chemicM bonding and optical properties of cubic Hf3N4 （ c-Hf3N4 ） are calculated using the first- principles based on the density functional theory （DFT）. The optimized lattice parameter is in good agreement with the available experimental and cedculational values. Band structure shows that c-Hf3N4 has direct band gap. Densities of states （DOS） and charge densities indicate that the bonding between Hf and N is ionic. The optical properties including complex dielectric function, refractive index, extinction coefficient, absorption coefficient, and refleetivity are predicted. Prom the theory of crystal-field and molecular-orbited bonding, the optical transitions of c-Hf3N4 affected by the electronic structure and molecular orbited are studied. It is found that the absorptive transitions of c-Hf3N4 compound are predominantly composed of the transitions from N T2 2p valence bands to Hf T2 （dxy, dxz, dyz） conduction bands.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.50902110the National Aerospace Science Foundation of China under Grant No.2008ZF53058+3 种基金 the Specialized Research Foundation for Doctoral Program of Higher Education of China under Grant No.200806991032 the Doctorate Foundation of Northwestern Polytechnical University under Grant No.cx201005 the Northwestern Polytechnical University (NPU) Foundation for Fundamental Research under Grant No.NPU-FFR-W018108the 111 Project under Grant No.B08040
文摘In order to clarify the mechanism of optical transitions for cubic SrHfO_3, we have investigated the electronicstructure and optical properties of cubic SrHfO_3 using the plane-wave ultrasoft pseudopotential technique based on thefirst-principles density-functional theory (DFT).The ground-state properties, obtained by minimizing the total energy,are in favorable agreement with the previous work.From the band structure and charge densities as well as the theoryof crystal-field and molecular-orbital bonding, we have systematically studied how the optical transitions are affected bythe electronic structure and molecular orbitals.Our calculated complex dielectric function is in good agreement withthe experimental data and the optical transitions are in accord with the electronic structure.
基金Supported by the National Natural Science Foundation of China(Nos.20401015 and 50574082)Beijing(China) Municipal Natural Science Foundation(No.2082022)the Innovation Project of the Chinese Academy of Sciences(Nos.CXJJ-171 and CXJJ-210)
文摘1 Introduction Since its first discovery in 1992, ordered mesoporous silica material with large pore size, high surface area, and high pore volume has attracted great attention for the potentially wide application in catalysis, adsorption, separation, and ion exchange, etc. However, the poor hydrothermal stability of mesoporous silica has limited its wide application in industry. Therefore, in the last 10 years, many studies have been dedicated to improving the hydrothermal stability of mesoporous silica. Xiao et al.
基金Supported by the National Natural Science Foundation of China under Grant No. 50902110the Natural Science Foundation of Shaanxi Province under Grant No. 2012JM6012+2 种基金the Research Fund of the State Key Laboratory of Solidification Processing under Grant No. 58TZ-2011the 111 Project under Grant No. B07040the Northwestern Polytechnical University Foundation for Fundamental Research under Grant No. JC20110245
文摘Electronic, chemicM bonding and optical properties of cubic Hf3N4 （ c-Hf3N4 ） are calculated using the first- principles based on the density functional theory （DFT）. The optimized lattice parameter is in good agreement with the available experimental and cedculational values. Band structure shows that c-Hf3N4 has direct band gap. Densities of states （DOS） and charge densities indicate that the bonding between Hf and N is ionic. The optical properties including complex dielectric function, refractive index, extinction coefficient, absorption coefficient, and refleetivity are predicted. Prom the theory of crystal-field and molecular-orbited bonding, the optical transitions of c-Hf3N4 affected by the electronic structure and molecular orbited are studied. It is found that the absorptive transitions of c-Hf3N4 compound are predominantly composed of the transitions from N T2 2p valence bands to Hf T2 （dxy, dxz, dyz） conduction bands.
