采用密度泛函理论(Density Function Theory)中的B3LYP方法,在Lanl2dz赝势基组水平上对(PtnMn)±,0(n=1~5)团簇的几何构型进行了全优化,并对基态的能级以及磁性进行了研究.结果表明:PtMn掺杂团簇的自旋多重度比较高,这种性质跟纯Mn...采用密度泛函理论(Density Function Theory)中的B3LYP方法,在Lanl2dz赝势基组水平上对(PtnMn)±,0(n=1~5)团簇的几何构型进行了全优化,并对基态的能级以及磁性进行了研究.结果表明:PtMn掺杂团簇的自旋多重度比较高,这种性质跟纯Mn团簇相似.并且发现一般情况下Mn原子参与成键数越多,结构越稳定,在成键数相同的情况下,成键的平均键长越短越稳定;其次(PtnMn)±,0团簇的所有稳定结构都表现为铁磁性耦合;掺杂一个Mn原子后的团簇磁性大大增强,磁矩主要来源于未满的d壳层电子,且Mn原子上的局域磁矩远大于Pt原子.随着Pt原子个数的增加,Mn原子的局域磁矩变化不大,但团簇的总磁矩渐渐增大.展开更多
We summarize the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions.The roles of configuration mixing,meson exchange currents and relativistic effects are examined.Experimen...We summarize the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions.The roles of configuration mixing,meson exchange currents and relativistic effects are examined.Experimental evidence for the importance of tensor correlations is also discussed.展开更多
Using the single particle states and the residual interaction derived from the relativistic point-coupling model with the PC-F1 parameter set,the second-order core polarization corrections to nuclear magnetic moments ...Using the single particle states and the residual interaction derived from the relativistic point-coupling model with the PC-F1 parameter set,the second-order core polarization corrections to nuclear magnetic moments of LS closed shell nuclei ±1 nucleon with A = 15,17,39 and 41 are studied and compared with previous non-relativistic results.It is found that the second-order corrections are significant.With these corrections,the isovector magnetic moments of the concerned nuclei are well reproduced,especially those for A = 17 and A = 41.展开更多
The magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the di...The magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the distribution amplitudes of the on-shell photon are used to extract the magnetic and quadrupole moments of these states.The magnetic moments are acquired asμZ_(c)=0.50+0.22−0.22μN,μZ_(c)^(1)=1.22+0.34−0.32μN,andμZ_(c)^(2)=2.40+0.53−0.48μN for the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states,respectively.The magnetic moments evaluated for the Z_(c)4020)+,Z_(c)(4050)+,and Z_(c)(4600)+states are sufficiently large to be experimentally measurable.The magnetic moment is an excellent platform for studying the internal structure of hadrons governed by the quark-gluon dynamics of QCD because it is the leading-order response of a bound system to a weak external magnetic field.The quadrupole moment results are DZ_(c)=(0.20+0.05−0.04)×10^(−3)fm^(2),DZ_(c)^(1)=(0.57+0.07−0.08)×10^(−3)fm^(2),and DZ_(c)^(2)=(0.30+0.05−0.04)×10^(−3)fm^(2)for the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states,respectively.We obtain a non-zero,but small,value for the quadrupole moments of the Z_(c)states,which indicates a non-spherical charge distribution.The nature and internal structure of these states can be elucidated by comparing future experimental data on the magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states with the results of the present study.展开更多
The anomalous magnetic(MDM)and electric(EDM)dipole moments of theτlepton serve as crucial indicators of new physics beyond the standard model.Leveraging azimuthal angular asymmetry as a novel tool in ultraperipheral ...The anomalous magnetic(MDM)and electric(EDM)dipole moments of theτlepton serve as crucial indicators of new physics beyond the standard model.Leveraging azimuthal angular asymmetry as a novel tool in ultraperipheral collisions(UPCs),we attain unparalleled precision in the study of these key properties.Driven by the highly linear polarization of coherent photons,this method uniquely enables both the MDM and EDM to contribute to the cos 2φangular distribution in similar magnitudes.Importantly,our approach substantially narrows the parameter space,excluding more than half of it compared to expected UPC-based measurements reliant solely on the total cross-section.This method not only provides improved constraints but also minimizes the need for additional theoretical assumptions,and offers a novel avenue to probe the EDM effects.展开更多
Computational calculations using density functional theory(DFT) were performed for the first time using the full potential linearized augmented plane wave plus local orbital method(FP-LAPW + LO) to determine the struc...Computational calculations using density functional theory(DFT) were performed for the first time using the full potential linearized augmented plane wave plus local orbital method(FP-LAPW + LO) to determine the structural, elastic, electronic and magnetic properties of europium-based cubic perovskites EuYO_(3)(Y=Cr, Mn, Fe). The exchange correlation potentials of GGA along with some analytical methods were adopted for the computation of structural and elastic properties. Moreover, the GGA + U formalism was also added for obtaining more precise electronic and magnetic properties, particularly to address the Eu-4f and Y-3d orientations in the spin-polarized double cell symmetry. The observed lattice parameters of these compounds are consistent with experiment. The observed bulk moduli predict that EuCrO_(3) is harder and less compressible than EuMnO_(3) and EuFeO_(3). The calculated tolerance factors of these compounds are within the cubic symmetry range. Our computed critical radius of EuCrO_(3) shows that EuCrO_(3) has a larger migration energy. Based on their elastic properties, these compounds are ductile in nature. We also computed the thermal properties of these compounds. The band structures and density of states show that these compounds are metallic in character. The lowest ground state energy and magnetic moments of these compounds expose their ferromagnetic nature. The metallic nature and strong ferromagnetism of these compounds make them promising applicants for application in spintronic.展开更多
Nickel is typically used as one of the main components in electrical contact devices or connectors.Nickel oxide(NiO)is usually formed on the surfaces of electrodes and can negatively impact system performance by intro...Nickel is typically used as one of the main components in electrical contact devices or connectors.Nickel oxide(NiO)is usually formed on the surfaces of electrodes and can negatively impact system performance by introducing electrical contact resistance.The thermal,electrical,and transport properties of NiO,as a Mott insulator or a p-type semiconductor,can be altered by operating and environmental conditions such as temperature and stress/strain by contact.In this study,we inves-tigate the fundamental material properties of NiO through the first-principle calculations.First,we obtain and compare the lattice parameter,magnetic moment,and electronic structure for NiO via the WIEN2K simulations with four different poten-tials(i.e.,GGA,GGA+U,LSDA,and LSDA+U).Then,using the WIEN2K simulation results with LSDA+U potential that produces a highly accurate bandgap for NiO,we calculate the electrical conductivity and electrical part of the thermal conductivity of nickel and NiO as a function of temperature and carrier concentration through the BoltzTraP simulations.Systematic simulation results revealed that the electrical conductivity relative to the relaxation time for NiO increases with the carrier concentration,while it shows a slightly decreasing trend with temperature under a fixed carrier concentration.By contrast,the electrical part of the thermal conductivity shows an increasing trend considering carrier concentration and temperature.展开更多
In this paper, based on the quasi-stationary magneto-hydrodynamic （MHD） model, vacuum arc characteristics are simulated and analyzed at different moments under power-frequency current. For a vacuum arc with sinusoid...In this paper, based on the quasi-stationary magneto-hydrodynamic （MHD） model, vacuum arc characteristics are simulated and analyzed at different moments under power-frequency current. For a vacuum arc with sinusoidal current under a uniform axial magnetic field （AMF）, simulation results show that at the moment of peak value current, maximal values appear in the ion number density, axial current density, heat flux density, electron temperature, plasma pressure and azimuthal magnetic field. At the same time, the distributions of these parameters along the radial position are mostly nonuniform as compared with those at other moments. In the first 1/4 cycle, the ion number density, axial current density and plasma pressure increase with time, but the growth rate decreases with time. Simulation results are partially compared with experimental results published in other papers. Simulations and light intensity near the cathode side is stronger than arcs. experimental results both show that the arc that near the anode side for diffusing vacuum展开更多
In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization inc...In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization increases proportionally with the number of SWNTs with sheared ends, suggesting that there exist magnetic moments at the sheared ends of SWNTs.By using the coefficient of this linear relation, the average magnetic moment is estimated to be 41.5 ± 9.8 μB(Bohr magneton) per carbon atom in the edge state at temperature of 300.0 K, suggesting that ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of the carbon atoms at sheared ends play important roles in determining the unexpectedly high magnetic moments, which may have great potential applications.展开更多
The renormalization of the orbital g-factor in nuclei is discussed on the basis of gauge invariance.The relation of the orbital g-factor to the integrated E1 photoabsorption cross section is reviewed,and its relation ...The renormalization of the orbital g-factor in nuclei is discussed on the basis of gauge invariance.The relation of the orbital g-factor to the integrated E1 photoabsorption cross section is reviewed,and its relation to the M1 sum rule for the scissors mode of deformed nuclei is examined.展开更多
文摘采用密度泛函理论(Density Function Theory)中的B3LYP方法,在Lanl2dz赝势基组水平上对(PtnMn)±,0(n=1~5)团簇的几何构型进行了全优化,并对基态的能级以及磁性进行了研究.结果表明:PtMn掺杂团簇的自旋多重度比较高,这种性质跟纯Mn团簇相似.并且发现一般情况下Mn原子参与成键数越多,结构越稳定,在成键数相同的情况下,成键的平均键长越短越稳定;其次(PtnMn)±,0团簇的所有稳定结构都表现为铁磁性耦合;掺杂一个Mn原子后的团簇磁性大大增强,磁矩主要来源于未满的d壳层电子,且Mn原子上的局域磁矩远大于Pt原子.随着Pt原子个数的增加,Mn原子的局域磁矩变化不大,但团簇的总磁矩渐渐增大.
文摘We summarize the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions.The roles of configuration mixing,meson exchange currents and relativistic effects are examined.Experimental evidence for the importance of tensor correlations is also discussed.
基金supported by the Major State Basic Research Developing Program (Grant No.2007CB815000)the National Natural Science Foundation of China(Grant Nos.10775004,10720003, 10947013, 10975008, 10975007, and 11005069)the Southwest University Initial Research Foundation Grant to Doctor (Grant No.SWU109011)
文摘Using the single particle states and the residual interaction derived from the relativistic point-coupling model with the PC-F1 parameter set,the second-order core polarization corrections to nuclear magnetic moments of LS closed shell nuclei ±1 nucleon with A = 15,17,39 and 41 are studied and compared with previous non-relativistic results.It is found that the second-order corrections are significant.With these corrections,the isovector magnetic moments of the concerned nuclei are well reproduced,especially those for A = 17 and A = 41.
文摘The magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the distribution amplitudes of the on-shell photon are used to extract the magnetic and quadrupole moments of these states.The magnetic moments are acquired asμZ_(c)=0.50+0.22−0.22μN,μZ_(c)^(1)=1.22+0.34−0.32μN,andμZ_(c)^(2)=2.40+0.53−0.48μN for the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states,respectively.The magnetic moments evaluated for the Z_(c)4020)+,Z_(c)(4050)+,and Z_(c)(4600)+states are sufficiently large to be experimentally measurable.The magnetic moment is an excellent platform for studying the internal structure of hadrons governed by the quark-gluon dynamics of QCD because it is the leading-order response of a bound system to a weak external magnetic field.The quadrupole moment results are DZ_(c)=(0.20+0.05−0.04)×10^(−3)fm^(2),DZ_(c)^(1)=(0.57+0.07−0.08)×10^(−3)fm^(2),and DZ_(c)^(2)=(0.30+0.05−0.04)×10^(−3)fm^(2)for the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states,respectively.We obtain a non-zero,but small,value for the quadrupole moments of the Z_(c)states,which indicates a non-spherical charge distribution.The nature and internal structure of these states can be elucidated by comparing future experimental data on the magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states with the results of the present study.
基金supported by the National Natural Science Foundation of China(Grant Nos.12275052,and 12147101)supported by the National Natural Science Foundation of China(Grant Nos.11725520,11675002,and 12235001)+1 种基金Shanghai Natural Science Foundation(Grant No.21ZR1406100)supported by the Institute of High Energy Physics(Contract No.E25153U1)。
文摘The anomalous magnetic(MDM)and electric(EDM)dipole moments of theτlepton serve as crucial indicators of new physics beyond the standard model.Leveraging azimuthal angular asymmetry as a novel tool in ultraperipheral collisions(UPCs),we attain unparalleled precision in the study of these key properties.Driven by the highly linear polarization of coherent photons,this method uniquely enables both the MDM and EDM to contribute to the cos 2φangular distribution in similar magnitudes.Importantly,our approach substantially narrows the parameter space,excluding more than half of it compared to expected UPC-based measurements reliant solely on the total cross-section.This method not only provides improved constraints but also minimizes the need for additional theoretical assumptions,and offers a novel avenue to probe the EDM effects.
基金Project supported by the Higher Education of Pakistan Under National Research Grant Program(NRPU)(Grant No:14408/NRPU/R&D/HEC/20212021)。
文摘Computational calculations using density functional theory(DFT) were performed for the first time using the full potential linearized augmented plane wave plus local orbital method(FP-LAPW + LO) to determine the structural, elastic, electronic and magnetic properties of europium-based cubic perovskites EuYO_(3)(Y=Cr, Mn, Fe). The exchange correlation potentials of GGA along with some analytical methods were adopted for the computation of structural and elastic properties. Moreover, the GGA + U formalism was also added for obtaining more precise electronic and magnetic properties, particularly to address the Eu-4f and Y-3d orientations in the spin-polarized double cell symmetry. The observed lattice parameters of these compounds are consistent with experiment. The observed bulk moduli predict that EuCrO_(3) is harder and less compressible than EuMnO_(3) and EuFeO_(3). The calculated tolerance factors of these compounds are within the cubic symmetry range. Our computed critical radius of EuCrO_(3) shows that EuCrO_(3) has a larger migration energy. Based on their elastic properties, these compounds are ductile in nature. We also computed the thermal properties of these compounds. The band structures and density of states show that these compounds are metallic in character. The lowest ground state energy and magnetic moments of these compounds expose their ferromagnetic nature. The metallic nature and strong ferromagnetism of these compounds make them promising applicants for application in spintronic.
基金Project supported by the National Major Fundamental Research Program of China (2007CB925001)National Key Fundamental Research Development Planning Program of China (001CB610604)Natural Science Research Program of Education Department of Anhui Province (2006KJ266B, ZD2007003-1)
文摘Nickel is typically used as one of the main components in electrical contact devices or connectors.Nickel oxide(NiO)is usually formed on the surfaces of electrodes and can negatively impact system performance by introducing electrical contact resistance.The thermal,electrical,and transport properties of NiO,as a Mott insulator or a p-type semiconductor,can be altered by operating and environmental conditions such as temperature and stress/strain by contact.In this study,we inves-tigate the fundamental material properties of NiO through the first-principle calculations.First,we obtain and compare the lattice parameter,magnetic moment,and electronic structure for NiO via the WIEN2K simulations with four different poten-tials(i.e.,GGA,GGA+U,LSDA,and LSDA+U).Then,using the WIEN2K simulation results with LSDA+U potential that produces a highly accurate bandgap for NiO,we calculate the electrical conductivity and electrical part of the thermal conductivity of nickel and NiO as a function of temperature and carrier concentration through the BoltzTraP simulations.Systematic simulation results revealed that the electrical conductivity relative to the relaxation time for NiO increases with the carrier concentration,while it shows a slightly decreasing trend with temperature under a fixed carrier concentration.By contrast,the electrical part of the thermal conductivity shows an increasing trend considering carrier concentration and temperature.
基金supported by Doctoral Fund of Ministry of Education of China (No.200806981052)National Natural Science Foundation of China (No.50907045)
文摘In this paper, based on the quasi-stationary magneto-hydrodynamic （MHD） model, vacuum arc characteristics are simulated and analyzed at different moments under power-frequency current. For a vacuum arc with sinusoidal current under a uniform axial magnetic field （AMF）, simulation results show that at the moment of peak value current, maximal values appear in the ion number density, axial current density, heat flux density, electron temperature, plasma pressure and azimuthal magnetic field. At the same time, the distributions of these parameters along the radial position are mostly nonuniform as compared with those at other moments. In the first 1/4 cycle, the ion number density, axial current density and plasma pressure increase with time, but the growth rate decreases with time. Simulation results are partially compared with experimental results published in other papers. Simulations and light intensity near the cathode side is stronger than arcs. experimental results both show that the arc that near the anode side for diffusing vacuum
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0208403 and 2016YFA0200403)the National Natural Science Foundation of China(Grant Nos.51472057,11874129,91323304,and 11674387)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA09040101)the Baotou Rare Earth Research and Development Centre,Chinese Academy of Sciences(Grant No.GZR 2018001)
文摘In this work we report that after single-walled carbon nanotubes(SWNTs) are sheared with a pair of titanium scissors,the magnetization becomes larger than that of the corresponding pristine ones. The magnetization increases proportionally with the number of SWNTs with sheared ends, suggesting that there exist magnetic moments at the sheared ends of SWNTs.By using the coefficient of this linear relation, the average magnetic moment is estimated to be 41.5 ± 9.8 μB(Bohr magneton) per carbon atom in the edge state at temperature of 300.0 K, suggesting that ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of the carbon atoms at sheared ends play important roles in determining the unexpectedly high magnetic moments, which may have great potential applications.
文摘The renormalization of the orbital g-factor in nuclei is discussed on the basis of gauge invariance.The relation of the orbital g-factor to the integrated E1 photoabsorption cross section is reviewed,and its relation to the M1 sum rule for the scissors mode of deformed nuclei is examined.
