The collective dynamics of magnetic domain wall under electric current is studied in the form of spin transfer torque(STT). The out-of-plane STT induced effective force is obtained based on the Landau-Lifshitz-Gilbert...The collective dynamics of magnetic domain wall under electric current is studied in the form of spin transfer torque(STT). The out-of-plane STT induced effective force is obtained based on the Landau-Lifshitz-Gilbert(LLG) equation including microscopic STT terms. The relation between microscopic calculations and collective description of the domain wall motion is established. With our numerical calculations based on tight binding free electron model, we find that the non adiabatic out-of-plane torque components have considerable non-local properties. It turns out that the calculated effective forces decay significantly with increasing domain wall widths.展开更多
采用基于密度泛函理论的第一性原理方法,研究了本征石墨烯及缺陷石墨烯对Na原子的吸附行为.主要研究了三种石墨烯:本征石墨烯、B掺杂的石墨烯和N掺杂的石墨烯.结果表明,与本征石墨烯相比,B掺杂的石墨烯和N掺杂的石墨烯在吸附能、电荷密...采用基于密度泛函理论的第一性原理方法,研究了本征石墨烯及缺陷石墨烯对Na原子的吸附行为.主要研究了三种石墨烯:本征石墨烯、B掺杂的石墨烯和N掺杂的石墨烯.结果表明,与本征石墨烯相比,B掺杂的石墨烯和N掺杂的石墨烯在吸附能、电荷密度、态密度和储钠量方面表现出很大的差异.B掺杂的石墨烯对Na原子的吸附能是-1.93 e V,约为本征石墨烯对Na原子吸附能的2.7倍;与本征石墨烯相比,N掺杂的石墨烯对Na原子的吸附能明显增大.态密度计算结果表明,Na原子与B掺杂的石墨烯中的B原子发生轨道杂化,而本征石墨烯和N掺杂的石墨烯中不存在轨道杂化现象.B掺杂的石墨烯对Na原子的吸附量是3个,与本征石墨烯相比显著提高.因此,B掺杂的石墨烯有望成为一种新型的储钠材料.展开更多
Two-dimensional layered double hydroxides(LDHs)have been identified as promising electrocatalysts for the oxygen evolution reaction(OER);however,the simple and effective synthesis of high-quality LDHs remains extremel...Two-dimensional layered double hydroxides(LDHs)have been identified as promising electrocatalysts for the oxygen evolution reaction(OER);however,the simple and effective synthesis of high-quality LDHs remains extremely challenging and the active sites have not been clarified.Herein,we report a facile solution-reaction method for preparing an ultrathin(thickness<2 nm)nonprecious CoFe-based LDH.Co_(1)Fe_(0.2) LDH delivers a current density of 10 mA cm^(-2) and a high turnover frequency of 0.082 s^(-1) per total 3d metal atoms at a low overpotential of 256 mV.Its mass activity is 277.9 A g^(-1) at an overpotential of 300 mV for the OER.Kinetic studies reveal the Co site as the main active center for the OER.The doped Fe lowers the reaction barrier by accelerating the charge-transfer process.Theoretical calculations reveal that the surface Co sites adjacent to Fe atoms are the active centers for the OER and the subsurface Fe dopants excessively weaken the OH^(*)adsorption,thus increasing the energy barrier of the rate-determining step.This study can guide the rational design of high-performance CoFe-based LDHs for water splitting.展开更多
To investigate the effects of chlorine on the Au/ceria catalysts,the adsorption of gold or chlorine and their coadsorpiton on the stoichiometric and partially reduced CeO2（111） surfaces are studied from the first pr...To investigate the effects of chlorine on the Au/ceria catalysts,the adsorption of gold or chlorine and their coadsorpiton on the stoichiometric and partially reduced CeO2（111） surfaces are studied from the first principles.It is found that the adsorption of Au is significantly enhanced by the chlorine preadsorption on the stoichiometric CeO2（111） surface;while on the partially reduced CeO2（111） surface,the preadsorbed chlorine inhabits the oxygen vacancy（which is the preferred adsorption site for gold）,leading to a CeOCl phase and the dramatical weakening of the Au adsorption.Therefore,chlorine on the CeO2（111） surface can affect the Au adsorption thus the activity of the Au/CeO2 catalyst.展开更多
The electronic structures, deformation charge density, dipole moment, and optical properties of N-La-codoped anatase titanium dioxide （TiO2） are studied using the plane-wave ultrasoft pseudopotential method based on...The electronic structures, deformation charge density, dipole moment, and optical properties of N-La-codoped anatase titanium dioxide （TiO2） are studied using the plane-wave ultrasoft pseudopotential method based on the density functional theory （DFT）. The optical properties of two-ion-doped TiO2 are analyzed via electronic structures, deformation charge density, and dipole moment. For the model of N-La-doped TiO2, a smaller atom fraction of N and La atoms induces better optical properties. The absorption edges of two doped TiO2 models redshift to the visible-light region.展开更多
Using ab initio total energy calculations with the full-potential linearized augmented plane wave method, the possibilities of magnetism in one-dimensional In and Tl wires were explored and their properties as the fun...Using ab initio total energy calculations with the full-potential linearized augmented plane wave method, the possibilities of magnetism in one-dimensional In and Tl wires were explored and their properties as the function of geometric structures were studied. The results suggest that the linear In and Tl wires show magnetization at the equilibrium bond distance with magnetic moments of 0.71 and 0.67 μB/atom, respectively. Allowing ions to relax, the wires were deformed as zigzag structures, but no dimerization occurs. The zigzag wires also exhibit spontaneous magnetization, although the magnetic moments are lower than those of straight wires.展开更多
基金supported by NSF of China(Grant No.60825405)MOST of China(2006CB933000)
文摘The collective dynamics of magnetic domain wall under electric current is studied in the form of spin transfer torque(STT). The out-of-plane STT induced effective force is obtained based on the Landau-Lifshitz-Gilbert(LLG) equation including microscopic STT terms. The relation between microscopic calculations and collective description of the domain wall motion is established. With our numerical calculations based on tight binding free electron model, we find that the non adiabatic out-of-plane torque components have considerable non-local properties. It turns out that the calculated effective forces decay significantly with increasing domain wall widths.
文摘采用基于密度泛函理论的第一性原理方法,研究了本征石墨烯及缺陷石墨烯对Na原子的吸附行为.主要研究了三种石墨烯:本征石墨烯、B掺杂的石墨烯和N掺杂的石墨烯.结果表明,与本征石墨烯相比,B掺杂的石墨烯和N掺杂的石墨烯在吸附能、电荷密度、态密度和储钠量方面表现出很大的差异.B掺杂的石墨烯对Na原子的吸附能是-1.93 e V,约为本征石墨烯对Na原子吸附能的2.7倍;与本征石墨烯相比,N掺杂的石墨烯对Na原子的吸附能明显增大.态密度计算结果表明,Na原子与B掺杂的石墨烯中的B原子发生轨道杂化,而本征石墨烯和N掺杂的石墨烯中不存在轨道杂化现象.B掺杂的石墨烯对Na原子的吸附量是3个,与本征石墨烯相比显著提高.因此,B掺杂的石墨烯有望成为一种新型的储钠材料.
文摘Two-dimensional layered double hydroxides(LDHs)have been identified as promising electrocatalysts for the oxygen evolution reaction(OER);however,the simple and effective synthesis of high-quality LDHs remains extremely challenging and the active sites have not been clarified.Herein,we report a facile solution-reaction method for preparing an ultrathin(thickness<2 nm)nonprecious CoFe-based LDH.Co_(1)Fe_(0.2) LDH delivers a current density of 10 mA cm^(-2) and a high turnover frequency of 0.082 s^(-1) per total 3d metal atoms at a low overpotential of 256 mV.Its mass activity is 277.9 A g^(-1) at an overpotential of 300 mV for the OER.Kinetic studies reveal the Co site as the main active center for the OER.The doped Fe lowers the reaction barrier by accelerating the charge-transfer process.Theoretical calculations reveal that the surface Co sites adjacent to Fe atoms are the active centers for the OER and the subsurface Fe dopants excessively weaken the OH^(*)adsorption,thus increasing the energy barrier of the rate-determining step.This study can guide the rational design of high-performance CoFe-based LDHs for water splitting.
基金Supported by the National Natural Science Foundation of China(61376099)the Foundation for Fundamental Research of China(JSZL2016110B003)the Major Fundamental Research Program of Shaanxi(2017ZDJC-26)
基金supported by the National Natural Science Foundation of China(Grant Nos.11174070,51401078,and 11147006)the China Postdoctoral Science Foundation(Grant No.2012M521399)+2 种基金the Postdoctoral Research Sponsorship in Henan Province,China(Grant No.2011038)the Foundation for the Key Young Teachers of Henan Normal UniversityStart-up Foundation for Doctors of Henan Normal University,China
文摘To investigate the effects of chlorine on the Au/ceria catalysts,the adsorption of gold or chlorine and their coadsorpiton on the stoichiometric and partially reduced CeO2（111） surfaces are studied from the first principles.It is found that the adsorption of Au is significantly enhanced by the chlorine preadsorption on the stoichiometric CeO2（111） surface;while on the partially reduced CeO2（111） surface,the preadsorbed chlorine inhabits the oxygen vacancy（which is the preferred adsorption site for gold）,leading to a CeOCl phase and the dramatical weakening of the Au adsorption.Therefore,chlorine on the CeO2（111） surface can affect the Au adsorption thus the activity of the Au/CeO2 catalyst.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50873047)
文摘The electronic structures, deformation charge density, dipole moment, and optical properties of N-La-codoped anatase titanium dioxide （TiO2） are studied using the plane-wave ultrasoft pseudopotential method based on the density functional theory （DFT）. The optical properties of two-ion-doped TiO2 are analyzed via electronic structures, deformation charge density, and dipole moment. For the model of N-La-doped TiO2, a smaller atom fraction of N and La atoms induces better optical properties. The absorption edges of two doped TiO2 models redshift to the visible-light region.
基金supported by the Natural Science Foundation of Henan Province(Grant No.82300443203)
文摘Using ab initio total energy calculations with the full-potential linearized augmented plane wave method, the possibilities of magnetism in one-dimensional In and Tl wires were explored and their properties as the function of geometric structures were studied. The results suggest that the linear In and Tl wires show magnetization at the equilibrium bond distance with magnetic moments of 0.71 and 0.67 μB/atom, respectively. Allowing ions to relax, the wires were deformed as zigzag structures, but no dimerization occurs. The zigzag wires also exhibit spontaneous magnetization, although the magnetic moments are lower than those of straight wires.
