A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Bu...A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory.The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration.The increasing Sb concentration induces the band gap narrowing.Optical transition has shifted to the low energy range with increasing Sb concentration.Other important optical constants such as the dielectric function,reflectivity,refractive index,and electron energy loss function for Sb-doped SnO2 are discussed.The optical absorption edge of SnO2 doped with Sb also shows a redshift.展开更多
We performed density functional theory calculations of H, C, and O chemisorption on the UN(001) and(111) surfaces using the generalized gradient approximation(GGA) and the Hubbard U parameter and revised Perdew-Burke-...We performed density functional theory calculations of H, C, and O chemisorption on the UN(001) and(111) surfaces using the generalized gradient approximation(GGA) and the Hubbard U parameter and revised Perdew-Burke-Ernzerhof(RPBE) exchange-correlation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. distance of molecules from UN(001) and UN(111) surfaces have been optimized for four symmetrical chemisorption sites, respectively. The results show that the Hollow, N-top, and Hollow adsorption sites are the most stable sites for H, C, and O atoms with chemisorption energies of 13.06,25.50 and 27.34 kJ/mol for UN(001) surface, respectively. From the point of adsorbent(UN(001) and UN(111)surfaces in this paper), interaction of O with the chemisorbed surface is of the maximum magnitude, then C and H, which are in agreement with electronegativities of individual atoms. For the UN(001) surface, U-N bond lengths change relatively little(< 9%) as a result of H chemisorption, however C and O chemisorptions result in remarkable changes for U-N bond lengths in interlayer(> 10%). Electronic structure calculations indicate that Bridge position is equivalent with Hollow position, and the most stable chemisorption position for H, C,and O atoms are all Bridge(or Hollow) position for the UN(111) surface. Calculated electronic density of states(DOSs) demonstrate electronic charge transfer between s, p orbitals in chemisorbed atoms and U 6d, 5f orbitals.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No. BUPT2009RC0412the National Natural Science Foundation of China under Grant Nos. 60908028 and 60971068
文摘A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory.The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration.The increasing Sb concentration induces the band gap narrowing.Optical transition has shifted to the low energy range with increasing Sb concentration.Other important optical constants such as the dielectric function,reflectivity,refractive index,and electron energy loss function for Sb-doped SnO2 are discussed.The optical absorption edge of SnO2 doped with Sb also shows a redshift.
基金Supported by National Natural Science Foundation of China(Nos.51401237,51271198 and 11474358)Self-Topics Fund of Xi’an Research Institute of High Technology(Nos.2014QNJJ018 and YX2012cxpy06)
文摘We performed density functional theory calculations of H, C, and O chemisorption on the UN(001) and(111) surfaces using the generalized gradient approximation(GGA) and the Hubbard U parameter and revised Perdew-Burke-Ernzerhof(RPBE) exchange-correlation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. distance of molecules from UN(001) and UN(111) surfaces have been optimized for four symmetrical chemisorption sites, respectively. The results show that the Hollow, N-top, and Hollow adsorption sites are the most stable sites for H, C, and O atoms with chemisorption energies of 13.06,25.50 and 27.34 kJ/mol for UN(001) surface, respectively. From the point of adsorbent(UN(001) and UN(111)surfaces in this paper), interaction of O with the chemisorbed surface is of the maximum magnitude, then C and H, which are in agreement with electronegativities of individual atoms. For the UN(001) surface, U-N bond lengths change relatively little(< 9%) as a result of H chemisorption, however C and O chemisorptions result in remarkable changes for U-N bond lengths in interlayer(> 10%). Electronic structure calculations indicate that Bridge position is equivalent with Hollow position, and the most stable chemisorption position for H, C,and O atoms are all Bridge(or Hollow) position for the UN(111) surface. Calculated electronic density of states(DOSs) demonstrate electronic charge transfer between s, p orbitals in chemisorbed atoms and U 6d, 5f orbitals.
