We give here an overview of the orbital-flee density functional theory that is used for modeling atoms and molecules. We review typical approximations to the kinetic energy, exchange-correlation corrections to the k...We give here an overview of the orbital-flee density functional theory that is used for modeling atoms and molecules. We review typical approximations to the kinetic energy, exchange-correlation corrections to the kinetic and Hartree energies, and constructions of the pseudopotentials. We discuss numerical discretizations for the orbital-free methods and include several numerical results for illustrations.展开更多
We studied the electronic structure of the two new transition-metal carbodiimides CoNCN and NiNCN using first-principles method, which is based on density-functional theory （DFT）. The density of states （DOS）, the ...We studied the electronic structure of the two new transition-metal carbodiimides CoNCN and NiNCN using first-principles method, which is based on density-functional theory （DFT）. The density of states （DOS）, the total energy of the cell and the spin magnetic moment of CoNCN and NiNCN were calculated. The calculations reveal that the compound CoNCN and NiNCN have hall-metallic properties in ferromagnetic ground state, and the spin magnetic moment per molecule is about 7.000 μB and 6.000 μB for CoNCN and NiNCN, respectively.展开更多
Electronic and optical properties of rock-salt AIN under high pressure are investigated by first-principlesmethod based on the plane-wave basis set.Analysis of band structures suggests that the rock-salt AIN has an in...Electronic and optical properties of rock-salt AIN under high pressure are investigated by first-principlesmethod based on the plane-wave basis set.Analysis of band structures suggests that the rock-salt AIN has an indirectgap of 4.53 eV,which is in good agreement with other results.By investigating the effects of pressure on the energygap,the different movement of conduction band at X point below and above 22.5 GPa is predicted.The opticalproperties including dielectric function,absorption,reflectivity,and refractive index are also calculated and analyzed.Itis found that the rock-salt AIN is transparent from the partially ultra-violet to the visible light area and hardly does thetransparence affected by the pressure.Furthermore,the curve of optical spectrum will shift to high energy area (blueshift) with increasing pressure.展开更多
The geometries and electronic spectra of a series of N-protonated corroles, including unsub- stituted H4Cor＋ and meso-triaryl substituted H4TPC＋, H4TpFPC＋, and H4TdCPC＋, were theoretically studied with density fun...The geometries and electronic spectra of a series of N-protonated corroles, including unsub- stituted H4Cor＋ and meso-triaryl substituted H4TPC＋, H4TpFPC＋, and H4TdCPC＋, were theoretically studied with density functional theory （DFT）. The results indicate that all these compounds have two conformers, one with C2 symmetry （denoted as Sl） is more stable than the other （denoted as $2, C1 symmetry） by 15.8-18.5 kJ/mol. The corrole macrocycles of these compounds show significant out-of-plane deformation. The enantiomerizations of the chiral S1 conformers were found to be a multi-step process with the $2 conformers as the intermediates. Electronic absorption spectra and electronic circular dichroism （ECD） of these compounds were calculated with time-dependent DFT. In comparison with H4Cor＋, the UV- Vis absorptions of meso-triaryl species are significantly red-shifted and their Q bands are enhanced due to the π-π conjugation between the aryl and corrole rings. Several neighboring electronic transitions were calculated with opposite signs in rotatory strengths, suggesting that ECD spectroscopy may be a useful tool in studying the electronic transitions of these compounds.展开更多
New writing systems for several of China’s minority languages were developed and implemented during a unique period in Chinese history.Throughout the different stages of modern Chinese history,these writing systems h...New writing systems for several of China’s minority languages were developed and implemented during a unique period in Chinese history.Throughout the different stages of modern Chinese history,these writing systems have had various societal functions and uses,including the improvement of education and literacy for China’s ethnic minorities.In the new era,the societal functions of these newly created systems have been weakened by the large-scale influence from both outside and within minority environment.Nevertheless,the newly created writing systems have undeniable value and significance,and they continue to serve positive functions that cannot be fulfilled by other writing systems.展开更多
基金supported by the National Science Foundation of China under the grant 10425105the National Basic Research Program under the grant 2005CB321704.
文摘We give here an overview of the orbital-flee density functional theory that is used for modeling atoms and molecules. We review typical approximations to the kinetic energy, exchange-correlation corrections to the kinetic and Hartree energies, and constructions of the pseudopotentials. We discuss numerical discretizations for the orbital-free methods and include several numerical results for illustrations.
文摘We studied the electronic structure of the two new transition-metal carbodiimides CoNCN and NiNCN using first-principles method, which is based on density-functional theory （DFT）. The density of states （DOS）, the total energy of the cell and the spin magnetic moment of CoNCN and NiNCN were calculated. The calculations reveal that the compound CoNCN and NiNCN have hall-metallic properties in ferromagnetic ground state, and the spin magnetic moment per molecule is about 7.000 μB and 6.000 μB for CoNCN and NiNCN, respectively.
基金National Natural Science Foundation of China under Grant Nos.10576020 and 10776022
文摘Electronic and optical properties of rock-salt AIN under high pressure are investigated by first-principlesmethod based on the plane-wave basis set.Analysis of band structures suggests that the rock-salt AIN has an indirectgap of 4.53 eV,which is in good agreement with other results.By investigating the effects of pressure on the energygap,the different movement of conduction band at X point below and above 22.5 GPa is predicted.The opticalproperties including dielectric function,absorption,reflectivity,and refractive index are also calculated and analyzed.Itis found that the rock-salt AIN is transparent from the partially ultra-violet to the visible light area and hardly does thetransparence affected by the pressure.Furthermore,the curve of optical spectrum will shift to high energy area (blueshift) with increasing pressure.
文摘The geometries and electronic spectra of a series of N-protonated corroles, including unsub- stituted H4Cor＋ and meso-triaryl substituted H4TPC＋, H4TpFPC＋, and H4TdCPC＋, were theoretically studied with density functional theory （DFT）. The results indicate that all these compounds have two conformers, one with C2 symmetry （denoted as Sl） is more stable than the other （denoted as $2, C1 symmetry） by 15.8-18.5 kJ/mol. The corrole macrocycles of these compounds show significant out-of-plane deformation. The enantiomerizations of the chiral S1 conformers were found to be a multi-step process with the $2 conformers as the intermediates. Electronic absorption spectra and electronic circular dichroism （ECD） of these compounds were calculated with time-dependent DFT. In comparison with H4Cor＋, the UV- Vis absorptions of meso-triaryl species are significantly red-shifted and their Q bands are enhanced due to the π-π conjugation between the aryl and corrole rings. Several neighboring electronic transitions were calculated with opposite signs in rotatory strengths, suggesting that ECD spectroscopy may be a useful tool in studying the electronic transitions of these compounds.
文摘New writing systems for several of China’s minority languages were developed and implemented during a unique period in Chinese history.Throughout the different stages of modern Chinese history,these writing systems have had various societal functions and uses,including the improvement of education and literacy for China’s ethnic minorities.In the new era,the societal functions of these newly created systems have been weakened by the large-scale influence from both outside and within minority environment.Nevertheless,the newly created writing systems have undeniable value and significance,and they continue to serve positive functions that cannot be fulfilled by other writing systems.
