Intermetallic compounds REIn_(3)(RE=rare earth)have attracted much attention due to their unique characteristics:crystal field effect,Kondo effect,superconductivity,heavy fermion,and antiferromagnetism,and their cobal...Intermetallic compounds REIn_(3)(RE=rare earth)have attracted much attention due to their unique characteristics:crystal field effect,Kondo effect,superconductivity,heavy fermion,and antiferromagnetism,and their cobalt diluted alloys exhibit the ferromagnetic half-metallic characteristics at room temperature.In this study,an empirical electron theory(EET)is employed to investigate systemically the valence electronic structure,the thermal and magnetic properties of REX_(3) and their cobalt diluted alloys for revealing the mechanism of physical properties.The calculated bond length,melting point,and magnetic moment match the experimental ones very well.The study reveals that structural stability and physical properties of REX_(3) and their cobalt dilute alloys are strongly related to their valence electron structures.It is suggested that the structural stability and cohesive energy depend upon the covalent electron,the melting point is modulated by covalent electron pair,and the magnetic moment is originated from 3d magnetic electron.The ferromagnetic characteristics of Co-diluted REIn3 alloys is originated from the introduction of strong ferromagnetic Co atom,but,a competition is caused between the electron transition from valence electron to magnetic electron on d orbit and its reversal electron transformation with increasing the content of cobalt,which results in the formations of diluted magnetic Gd(In,Co)_(3) alloy with minor amount of cobalt and strong magnetic Nd(In,Co)_(3) alloy with doping more Co atoms.展开更多
Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Her...Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.展开更多
The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the re...The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the realization of superconductivity in compressively strained La_(3)Ni_(2)O_(7)thin films grown on the SrLaAlO_(4)substrates,with a T_(c)exceeding 40 K,represents a significant step toward this goal.Here,we investigate the influence of film thickness and carrier doping on the electronic structure of La_(3)Ni_(2)O_(7)thin films,ranging from 0.5 to 3 unit cells,using first-principles calculations.For a 2 unit-cell film with an optimal doping concentration of 0.3 hole per formula unit(0.15 hole/Ni),the Ni-d_(z^(2))interlayer bonding state crosses the Fermi level,resulting in the formation ofγpockets at the Fermi surface.These findings align with angle-resolved photoemission spectroscopy experimental data.Our results provide theoretical validation for the recent experimental discovery of ambient-pressure superconductivity in La_(3)Ni_(2)O_(7)thin films and underscore the significant impact of film thickness and carrier doping on electronic property modulation.展开更多
The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclus...The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclusively observed in thin films under atmospheric pressure,underscoring the critical role of the heterointerface.展开更多
Diradicaloid polycyclic hydrocarbons(PHs)own unique open-shell electronic structures and exhibit potential utility in the fields of organic electronics and spintronics.Herein,we disclose precise fusion of B/O-heterocy...Diradicaloid polycyclic hydrocarbons(PHs)own unique open-shell electronic structures and exhibit potential utility in the fields of organic electronics and spintronics.Herein,we disclose precise fusion of B/O-heterocycles onto PHs for control over their electronic structures and diradical properties.We designed and synthesized four B/O-containing diradicaloid isomers that feature the fluoreno[3,2-b]fluorene and fluoreno[2,1-a]fluoreneπ-skeletons,respectively.The precise B/O-heterocycle fusion modes along with the changed conjugation patterns lead to their modulated electronic structures and properties,such as diradical and aromatic structures,energy levels and band gaps,as well as magnetic,electrochemical and photophysical properties.Notably,the mode A may decrease the open-shell extent,whereas the mode B can enhance the diradical nature,leading to their well-tuned diradical characters in the range of0.46-0.70.Moreover,the mode A stabilizes the LUMOs and the mode B obviously increases the HOMO levels,which are remarkably contributed by the B and O atoms,respectively,further giving rise to the decreased band gaps and redshifted absorptions.This study clearly illustrates the electronic effects of B/O-heterocycle fusion on PHs and gains insight into B/O-type organic diradicaloids.These findings will provide an important guideline for the design of more fascinating heteroatom-containing diradicaloids.展开更多
Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled t...Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.展开更多
Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and v...Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and viable quantum algorithms for simulating large-scale materials are still limited.We propose and implement random-state quantum algorithms to calculate electronic-structure properties of real materials.Using a random state circuit on a small number of qubits,we employ real-time evolution with first-order Trotter decomposition and Hadamard test to obtain electronic density of states,and we develop a modified quantum phase estimation algorithm to calculate real-space local density of states via direct quantum measurements.Furthermore,we validate these algorithms by numerically computing the density of states and spatial distributions of electronic states in graphene,twisted bilayer graphene quasicrystals,and fractal lattices,covering system sizes from hundreds to thousands of atoms.Our results manifest that the random-state quantum algorithms provide a general and qubit-efficient route to scalable simulations of electronic properties in large-scale periodic and aperiodic materials.展开更多
The electronic structures and optical properties of rocksalt indium nitride （INN） under pressure were studied using the first-principles calculation by considering the exchange and correlation potentials with the ge...The electronic structures and optical properties of rocksalt indium nitride （INN） under pressure were studied using the first-principles calculation by considering the exchange and correlation potentials with the generalized gradient approximation. The calculated lattice constant shows good agreement with the experimental value. It is interestingly found that the band gap energy Eg at the F or X point remarkably increases with increasing pressure, but Eg at the L point does not increase obviously. The pressure coefficient of Eg is calculated to be 44 meV/GPa at the F point. Moreover, the optical properties of rocksalt InN were calculated and discussed based on the calculated band structures and electronic density of states.展开更多
We investigate the electronic and magnetic properties of the diluted magnetic semiconductors Zn1-xMnxS（001） thin films with different Mn doping concentrations using the total energy density functional theory. The en...We investigate the electronic and magnetic properties of the diluted magnetic semiconductors Zn1-xMnxS（001） thin films with different Mn doping concentrations using the total energy density functional theory. The energy stability and density of states of a single Mn atom and two Mn atoms at various doped configurations and different magnetic coupling state were calculated. Different doping configurations have different degrees of p-d hybridization, and because Mn atoms are located in different crystal-field environment, the 3d projected densities of states peak splitting of different Mn doping configurations are quite different. In the two Mn atoms doped, the calculated ground states of three kinds of stable configurations are anti-ferromagnetic state. We analyzed the 3d density of states diagram of three kinds of energy stability configurations with the two Mn atoms in different magnetic coupling state. When the two Mn atoms are ferromagnetic coupling, due to d-d electron interactions, density of states of anti-bonding state have significant broadening peaks. As the concentration of Mn atoms increases, there is a tendency for Mn atoms to form nearest neighbors and cluster around S. For such these configurations, the antiferromagnetic coupling between Mn atoms is energetically more favorable.展开更多
A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant.The phase structure,morphology an...A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant.The phase structure,morphology and photoluminescence properties were measured by powder X-ray diffraction,scanning electron microscope and fluorescence spectrometer,respectively.The results show that uniform spherical microcrystals with diameters in the range of 2–4μm are obtained.And the phase and morphology of samples are not significantly changed by doping rare earth(RE^(3+))ions.Under the excitation wavelength of 356 and 365 nm,the samples BaWO 4:0.03Dy^(3+),yTm^(3+)can emit cold white light.In order to lower the correlated color temperature(CCT)to get a warm white light,the Eu^(3+)ions were doped into BaWO 4:0.03Dy^(3+),0.01Tm^(3+).Especially,under the excitation of 365 nm,BaWO 4:0.03Dy^(3+),0.01Tm^(3+),0.03Eu^(3+)phosphor shew a bright warm white light with color coordi-nate of(0.4013,0.3629)and CCT of 3288 K.Moreover,in the BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors,the energy transfer mechanism among Dy^(3+),Tm^(3+)and Eu^(3+)ions have been discussed and the change of electron structures have been calculated by first-principles calculations.The results shew that the uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors could be favorable candidates in warm white LEDs.展开更多
To better understand the relative stability and bonding characteristics of the L12, D022 and D023 structures for HfAl3, the formation enthalpies, electronic structures and thermodynamics properties were investigated b...To better understand the relative stability and bonding characteristics of the L12, D022 and D023 structures for HfAl3, the formation enthalpies, electronic structures and thermodynamics properties were investigated by first-principles calculations. The agreement of calculated equilibrium lattice parameters and formation enthalpies with experimental results indicates the reliability of this work. The order of structural stability is D023〉D022〉L12. The results of densities of states, atomic Mulliken charge and bond population support the best structural stability for D023 structure. Variations of thermodynamic properties with temperature were predicted via phonon frequencies calculation. The enthalpy, entropy, free energy of D023 structure change more quickly than those of the other two structures. The Debye temperatures of L12, D022 and D023 structures are 399, 407 and 416 K, respectively. The volume thermal expansions for HfAl3 increase exponentially at the low temperature, whereas the thermal expansion coefficients increase linearly at the high temperature.展开更多
The phase stability,elastic properties and electronic structures of three typical Mg-Y intermetallics including Mg_(24)Y_(5),Mg_(2)Y and MgY are systematically investigated using first-principles calculations based on...The phase stability,elastic properties and electronic structures of three typical Mg-Y intermetallics including Mg_(24)Y_(5),Mg_(2)Y and MgY are systematically investigated using first-principles calculations based on density functional theory.The optimized structural parameters including lattice constants and atomic coordinates are in good agreement with experimental values.The calculated cohesive energies and formation enthalpies show that either phase stability or alloying ability of the three intermetallics is gradually enhanced with increasing Y content.The single-crystal elastic constants C_(ij) of Mg-Y intermetallics are also calculated,and the bulk modulus B,shear modulus G,Young's modulus E,Poisson ratio v and anisotropy factor A of polycrystalline materials are derived.It is suggested that the resistances to volume and shear deformation as well as the stiffness of the three intermetallics are raised with increasing Y content.Besides,these intermetallics all exhibit ductile characteristics,and they are isotropic in compression but anisotropic to a certain degree in shear and stiffness.Comparatively,Mg_(24)Y_(5) presents a relatively higher ductility,while MgY has a relatively stronger anisotropy in shear and stiffness.Further analysis of electronic structures indicates that the phase stability of Mg-Y intermetallics is closely related with their bonding electrons numbers below Fermi level.Namely,the more bonding electrons number below Fermi level corresponds to the higher structural stability of Mg-Y intermetallics.展开更多
The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band ...The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.展开更多
The electronic structures of pure V, Nb and Ta metals with bcc structure were determined by one atom (OA) theory. According to the electronic structures of these metals, their potential curves, cohesive energies, latt...The electronic structures of pure V, Nb and Ta metals with bcc structure were determined by one atom (OA) theory. According to the electronic structures of these metals, their potential curves, cohesive energies, lattice parameters, elasticity and the dependence of linear thermal expansion coefficients on temperature were calculated. The electronic structures and characteristic properties of these metals with fcc and hcp structures and liquid states were studied.展开更多
First-principle calculations with different exchange-correlation functionals, including LDA, PBE, and vd W-DF functional in the form of opt B88-vd W, have been performed to investigate the electronic and elastic prope...First-principle calculations with different exchange-correlation functionals, including LDA, PBE, and vd W-DF functional in the form of opt B88-vd W, have been performed to investigate the electronic and elastic properties of twodimensional transition metal dichalcogenides（TMDCs） with the formula of MX2（M = Mo, W; X = O, S, Se, Te） in both monolayer and bilayer structures. The calculated band structures show a direct band gap for monolayer TMDCs at the K point except for MoO2 and WO2. When the monolayers are stacked into a bilayer, the reduced indirect band gaps are found except for bilayer WTe2, in which the direct gap is still present at the K point. The calculated in-plane Young moduli are comparable to that of graphene, which promises possible application of TMDCs in future flexible and stretchable electronic devices. We also evaluated the performance of different functionals including LDA, PBE, and opt B88-vd W in describing elastic moduli of TMDCs and found that LDA seems to be the most qualified method. Moreover, our calculations suggest that the Young moduli for bilayers are insensitive to stacking orders and the mechanical coupling between monolayers seems to be negligible.展开更多
The influence of Li intercalation on the electronic structures of oxygen and vanadium ions in α-V205 was investigated using first-principles calculations based on the density functional theory with local density appr...The influence of Li intercalation on the electronic structures of oxygen and vanadium ions in α-V205 was investigated using first-principles calculations based on the density functional theory with local density approximation. Two different intercalation sites for Li in the V205 lattices were considered. The calculation results demonstrate that intercalated Li ions at different sites show different effects on the electronic structures of O2p and V3d orbitals. But in both cases Li intercalation will weaken the V---O1 bonding and cause the split-off in V3d valence band to narrow or even disappear and simultaneously broaden the O2p conduction band. Further, the average electron transfer number from per intercalated Li2s to V3d orbitals is determined to total be about 0.52.展开更多
High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high hardness.In the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bondin...High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high hardness.In the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bonding charge density,and hardness of HEBs are comprehensively investigated by the first-principles calculations,including(TiZrHfNbTa)B_(2),(TiZrHfNbMo)B_(2),(TiZrHfTaMo)B_(2),(TiZrNbTaMo)B_(2),and(TiHfNbTaMo)B_(2).It is revealed that the disordered TM atoms result in a severe local lattice distortion and the formation of weak spots.In view of bonding charge density,it is understood that the degree of electron contribution of TM atoms directly affects the bonding strength of the metallic layer,contributing to the optimized hardness of HEBs.Moreover,the proposed power-law-scaled relationship integrating the EWF and the grain size yields an excellent agreement between our predicted results and those reported experimental ones.It is found that the HEBs exhibit relatively high hardness which is higher than those of single transition metal diborides.In particular,the hardness of(TiZrNbTaMo)B_(2)and(TiHfNbTaMo)B_(2)can be as high as29.15 and 28.02 GPa,respectively.This work provides a rapid strategy to discover/design advanced HEBs efficiently,supported by the coupling hardening mechanisms of solid solution and grain refinement based on the atomic and electronic interactions.展开更多
The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In additio...The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dix-anthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order： As-substituted 〈 perfect 〈 Co-substituted 〈 intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidi-zation compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S Fe bond is larger compared to the S S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S Fe bond and a decrease in the covalence level of the S S bond, which affect the natural floatability of the pyrites.展开更多
Montmorillonite is a kind of clay mineral which often causes large deformation in soft-rock tunnel engineering and thus brings about safety problems in practice.To deal with these engineering safety problems,the physi...Montmorillonite is a kind of clay mineral which often causes large deformation in soft-rock tunnel engineering and thus brings about safety problems in practice.To deal with these engineering safety problems,the physical and chemical properties of montmorillonite should be studied from basic viewpoints.We study the atomic and electronic structures of montmorillonite by using density-functional theory within the local-density approximation （LDA）.The results of calculation show that Al-O bond lengths are longer than Si-O bond lengths.It is found that both the valence band maximum （VBM） and the conduction band minimum （CBM） of montmorillonite are at point Г,and the calculated direct band gap of montmorillonite is 5.35 eV. We show that the chemical bonding between cations and oxygen anions in montmorillonite is mainly ionic,accompanied as well by a minor covalent component.It is pointed out that the VBM and CBM of montmorillonite consist of oxygen 2p and cation s states,respectively.Our calculated results help to understand the chemical and physical properties of montmorillonite,and are expected to be a guide for solving the problem of large deformation of soft-rock tunnels.展开更多
文摘Intermetallic compounds REIn_(3)(RE=rare earth)have attracted much attention due to their unique characteristics:crystal field effect,Kondo effect,superconductivity,heavy fermion,and antiferromagnetism,and their cobalt diluted alloys exhibit the ferromagnetic half-metallic characteristics at room temperature.In this study,an empirical electron theory(EET)is employed to investigate systemically the valence electronic structure,the thermal and magnetic properties of REX_(3) and their cobalt diluted alloys for revealing the mechanism of physical properties.The calculated bond length,melting point,and magnetic moment match the experimental ones very well.The study reveals that structural stability and physical properties of REX_(3) and their cobalt dilute alloys are strongly related to their valence electron structures.It is suggested that the structural stability and cohesive energy depend upon the covalent electron,the melting point is modulated by covalent electron pair,and the magnetic moment is originated from 3d magnetic electron.The ferromagnetic characteristics of Co-diluted REIn3 alloys is originated from the introduction of strong ferromagnetic Co atom,but,a competition is caused between the electron transition from valence electron to magnetic electron on d orbit and its reversal electron transformation with increasing the content of cobalt,which results in the formations of diluted magnetic Gd(In,Co)_(3) alloy with minor amount of cobalt and strong magnetic Nd(In,Co)_(3) alloy with doping more Co atoms.
基金supported by National Natural Science Foundation of China(No.523B2070,No.52225606).
文摘Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.
基金supported by the National Key R&D Program of China(Gran Nos.2022YFA1402304 and 2022YFA1402802)the National Natural Science Foundation of China(Grant Nos.12494591,12122405,12274169,and 92165204)+4 种基金Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)Guangdong Fundamental Research Center for Magnetoelectric Physics(2024B0303390001)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2401010)the Fundamental Research Funds for the Central Universities。
文摘The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the realization of superconductivity in compressively strained La_(3)Ni_(2)O_(7)thin films grown on the SrLaAlO_(4)substrates,with a T_(c)exceeding 40 K,represents a significant step toward this goal.Here,we investigate the influence of film thickness and carrier doping on the electronic structure of La_(3)Ni_(2)O_(7)thin films,ranging from 0.5 to 3 unit cells,using first-principles calculations.For a 2 unit-cell film with an optimal doping concentration of 0.3 hole per formula unit(0.15 hole/Ni),the Ni-d_(z^(2))interlayer bonding state crosses the Fermi level,resulting in the formation ofγpockets at the Fermi surface.These findings align with angle-resolved photoemission spectroscopy experimental data.Our results provide theoretical validation for the recent experimental discovery of ambient-pressure superconductivity in La_(3)Ni_(2)O_(7)thin films and underscore the significant impact of film thickness and carrier doping on electronic property modulation.
基金supported by the National Natural Science Foundation of China[52125307(to P.G.),12404192(to R.C.S),12274061(to L.Q.)]Key Research and Development Program from the Ministry of Science and Technology(2023YFA1406301)the support from the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclusively observed in thin films under atmospheric pressure,underscoring the critical role of the heterointerface.
基金supported by National Natural Science Foundation of China(Nos.52373182 and 22175074)Jilin Scientific and Technological Development Program(No.20220101054JC)Department of Education of Jilin Province(No.JJKH20221046KJ)。
文摘Diradicaloid polycyclic hydrocarbons(PHs)own unique open-shell electronic structures and exhibit potential utility in the fields of organic electronics and spintronics.Herein,we disclose precise fusion of B/O-heterocycles onto PHs for control over their electronic structures and diradical properties.We designed and synthesized four B/O-containing diradicaloid isomers that feature the fluoreno[3,2-b]fluorene and fluoreno[2,1-a]fluoreneπ-skeletons,respectively.The precise B/O-heterocycle fusion modes along with the changed conjugation patterns lead to their modulated electronic structures and properties,such as diradical and aromatic structures,energy levels and band gaps,as well as magnetic,electrochemical and photophysical properties.Notably,the mode A may decrease the open-shell extent,whereas the mode B can enhance the diradical nature,leading to their well-tuned diradical characters in the range of0.46-0.70.Moreover,the mode A stabilizes the LUMOs and the mode B obviously increases the HOMO levels,which are remarkably contributed by the B and O atoms,respectively,further giving rise to the decreased band gaps and redshifted absorptions.This study clearly illustrates the electronic effects of B/O-heterocycle fusion on PHs and gains insight into B/O-type organic diradicaloids.These findings will provide an important guideline for the design of more fascinating heteroatom-containing diradicaloids.
基金supported by the Research Project on Strengthening the Construction of an Important Ecological Security Barrier in Northern China by Higher Education Institutions in the Inner Mongolia Autonomous Region(STAQZX202313)the Inner Mongolia Autonomous Region Education Science‘14th Five-Year Plan’2024 Annual Research Project(NGJGH2024635).
文摘Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.
基金supported by the Major Project for the Integration of ScienceEducation and Industry (Grant No.2025ZDZX02)。
文摘Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and viable quantum algorithms for simulating large-scale materials are still limited.We propose and implement random-state quantum algorithms to calculate electronic-structure properties of real materials.Using a random state circuit on a small number of qubits,we employ real-time evolution with first-order Trotter decomposition and Hadamard test to obtain electronic density of states,and we develop a modified quantum phase estimation algorithm to calculate real-space local density of states via direct quantum measurements.Furthermore,we validate these algorithms by numerically computing the density of states and spatial distributions of electronic states in graphene,twisted bilayer graphene quasicrystals,and fractal lattices,covering system sizes from hundreds to thousands of atoms.Our results manifest that the random-state quantum algorithms provide a general and qubit-efficient route to scalable simulations of electronic properties in large-scale periodic and aperiodic materials.
文摘The electronic structures and optical properties of rocksalt indium nitride （INN） under pressure were studied using the first-principles calculation by considering the exchange and correlation potentials with the generalized gradient approximation. The calculated lattice constant shows good agreement with the experimental value. It is interestingly found that the band gap energy Eg at the F or X point remarkably increases with increasing pressure, but Eg at the L point does not increase obviously. The pressure coefficient of Eg is calculated to be 44 meV/GPa at the F point. Moreover, the optical properties of rocksalt InN were calculated and discussed based on the calculated band structures and electronic density of states.
基金This work was supported by the National Natural Science Foundation of China （No.60776039 and No.60406005）, the Natural Science Foundation of Beijing （No.3062016）, and the School Foundation of Beijing Jiaotong University.
文摘We investigate the electronic and magnetic properties of the diluted magnetic semiconductors Zn1-xMnxS（001） thin films with different Mn doping concentrations using the total energy density functional theory. The energy stability and density of states of a single Mn atom and two Mn atoms at various doped configurations and different magnetic coupling state were calculated. Different doping configurations have different degrees of p-d hybridization, and because Mn atoms are located in different crystal-field environment, the 3d projected densities of states peak splitting of different Mn doping configurations are quite different. In the two Mn atoms doped, the calculated ground states of three kinds of stable configurations are anti-ferromagnetic state. We analyzed the 3d density of states diagram of three kinds of energy stability configurations with the two Mn atoms in different magnetic coupling state. When the two Mn atoms are ferromagnetic coupling, due to d-d electron interactions, density of states of anti-bonding state have significant broadening peaks. As the concentration of Mn atoms increases, there is a tendency for Mn atoms to form nearest neighbors and cluster around S. For such these configurations, the antiferromagnetic coupling between Mn atoms is energetically more favorable.
基金This work was supported by Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant.The phase structure,morphology and photoluminescence properties were measured by powder X-ray diffraction,scanning electron microscope and fluorescence spectrometer,respectively.The results show that uniform spherical microcrystals with diameters in the range of 2–4μm are obtained.And the phase and morphology of samples are not significantly changed by doping rare earth(RE^(3+))ions.Under the excitation wavelength of 356 and 365 nm,the samples BaWO 4:0.03Dy^(3+),yTm^(3+)can emit cold white light.In order to lower the correlated color temperature(CCT)to get a warm white light,the Eu^(3+)ions were doped into BaWO 4:0.03Dy^(3+),0.01Tm^(3+).Especially,under the excitation of 365 nm,BaWO 4:0.03Dy^(3+),0.01Tm^(3+),0.03Eu^(3+)phosphor shew a bright warm white light with color coordi-nate of(0.4013,0.3629)and CCT of 3288 K.Moreover,in the BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors,the energy transfer mechanism among Dy^(3+),Tm^(3+)and Eu^(3+)ions have been discussed and the change of electron structures have been calculated by first-principles calculations.The results shew that the uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors could be favorable candidates in warm white LEDs.
基金Project(2015HB019)supported by the Reserve Talents Project of Yunnan Province,ChinaProject(2015Z038)supported by the Scientific Research Fund of Department of Education of Yunnan Province,China
文摘To better understand the relative stability and bonding characteristics of the L12, D022 and D023 structures for HfAl3, the formation enthalpies, electronic structures and thermodynamics properties were investigated by first-principles calculations. The agreement of calculated equilibrium lattice parameters and formation enthalpies with experimental results indicates the reliability of this work. The order of structural stability is D023〉D022〉L12. The results of densities of states, atomic Mulliken charge and bond population support the best structural stability for D023 structure. Variations of thermodynamic properties with temperature were predicted via phonon frequencies calculation. The enthalpy, entropy, free energy of D023 structure change more quickly than those of the other two structures. The Debye temperatures of L12, D022 and D023 structures are 399, 407 and 416 K, respectively. The volume thermal expansions for HfAl3 increase exponentially at the low temperature, whereas the thermal expansion coefficients increase linearly at the high temperature.
基金This work was financially supported by the National Natural Science Foundation of China(No.51401036)the Hunan Provincial Natural Science Foundation of China(No.14JJ3086),the Research Foundation of Education Bureau of Hunan Province(No.12B001)the Key Laboratory of Efficient and Clean Energy Utilization,College of Hunan Province(No.2015NGQ005).
文摘The phase stability,elastic properties and electronic structures of three typical Mg-Y intermetallics including Mg_(24)Y_(5),Mg_(2)Y and MgY are systematically investigated using first-principles calculations based on density functional theory.The optimized structural parameters including lattice constants and atomic coordinates are in good agreement with experimental values.The calculated cohesive energies and formation enthalpies show that either phase stability or alloying ability of the three intermetallics is gradually enhanced with increasing Y content.The single-crystal elastic constants C_(ij) of Mg-Y intermetallics are also calculated,and the bulk modulus B,shear modulus G,Young's modulus E,Poisson ratio v and anisotropy factor A of polycrystalline materials are derived.It is suggested that the resistances to volume and shear deformation as well as the stiffness of the three intermetallics are raised with increasing Y content.Besides,these intermetallics all exhibit ductile characteristics,and they are isotropic in compression but anisotropic to a certain degree in shear and stiffness.Comparatively,Mg_(24)Y_(5) presents a relatively higher ductility,while MgY has a relatively stronger anisotropy in shear and stiffness.Further analysis of electronic structures indicates that the phase stability of Mg-Y intermetallics is closely related with their bonding electrons numbers below Fermi level.Namely,the more bonding electrons number below Fermi level corresponds to the higher structural stability of Mg-Y intermetallics.
文摘The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.
文摘The electronic structures of pure V, Nb and Ta metals with bcc structure were determined by one atom (OA) theory. According to the electronic structures of these metals, their potential curves, cohesive energies, lattice parameters, elasticity and the dependence of linear thermal expansion coefficients on temperature were calculated. The electronic structures and characteristic properties of these metals with fcc and hcp structures and liquid states were studied.
基金Project supported by the Construct Program of the Key Discipline in Hunan Province,ChinaAid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,China
文摘First-principle calculations with different exchange-correlation functionals, including LDA, PBE, and vd W-DF functional in the form of opt B88-vd W, have been performed to investigate the electronic and elastic properties of twodimensional transition metal dichalcogenides（TMDCs） with the formula of MX2（M = Mo, W; X = O, S, Se, Te） in both monolayer and bilayer structures. The calculated band structures show a direct band gap for monolayer TMDCs at the K point except for MoO2 and WO2. When the monolayers are stacked into a bilayer, the reduced indirect band gaps are found except for bilayer WTe2, in which the direct gap is still present at the K point. The calculated in-plane Young moduli are comparable to that of graphene, which promises possible application of TMDCs in future flexible and stretchable electronic devices. We also evaluated the performance of different functionals including LDA, PBE, and opt B88-vd W in describing elastic moduli of TMDCs and found that LDA seems to be the most qualified method. Moreover, our calculations suggest that the Young moduli for bilayers are insensitive to stacking orders and the mechanical coupling between monolayers seems to be negligible.
基金This work was supported of by the National Natural Science Foundation of China （No.20603028）, the Project of Young Talents Innovation of Fujian Province （No.2005J005）, and the Project of New Century Excel- lent Talent of Fujian Province.
文摘The influence of Li intercalation on the electronic structures of oxygen and vanadium ions in α-V205 was investigated using first-principles calculations based on the density functional theory with local density approximation. Two different intercalation sites for Li in the V205 lattices were considered. The calculation results demonstrate that intercalated Li ions at different sites show different effects on the electronic structures of O2p and V3d orbitals. But in both cases Li intercalation will weaken the V---O1 bonding and cause the split-off in V3d valence band to narrow or even disappear and simultaneously broaden the O2p conduction band. Further, the average electron transfer number from per intercalated Li2s to V3d orbitals is determined to total be about 0.52.
基金financially supported by the Science Challenge Project(No.TZ 2018002)。
文摘High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high hardness.In the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bonding charge density,and hardness of HEBs are comprehensively investigated by the first-principles calculations,including(TiZrHfNbTa)B_(2),(TiZrHfNbMo)B_(2),(TiZrHfTaMo)B_(2),(TiZrNbTaMo)B_(2),and(TiHfNbTaMo)B_(2).It is revealed that the disordered TM atoms result in a severe local lattice distortion and the formation of weak spots.In view of bonding charge density,it is understood that the degree of electron contribution of TM atoms directly affects the bonding strength of the metallic layer,contributing to the optimized hardness of HEBs.Moreover,the proposed power-law-scaled relationship integrating the EWF and the grain size yields an excellent agreement between our predicted results and those reported experimental ones.It is found that the HEBs exhibit relatively high hardness which is higher than those of single transition metal diborides.In particular,the hardness of(TiZrNbTaMo)B_(2)and(TiHfNbTaMo)B_(2)can be as high as29.15 and 28.02 GPa,respectively.This work provides a rapid strategy to discover/design advanced HEBs efficiently,supported by the coupling hardening mechanisms of solid solution and grain refinement based on the atomic and electronic interactions.
基金supported by the National Natural Science Foundation of China (No.u0837602)
文摘The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dix-anthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order： As-substituted 〈 perfect 〈 Co-substituted 〈 intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidi-zation compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S Fe bond is larger compared to the S S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S Fe bond and a decrease in the covalence level of the S S bond, which affect the natural floatability of the pyrites.
基金Project supported by the National Key Basic Research Program of China (Grant No 2006CB202200)the Program for Changjiang Scholars and Innovative Research Team in University of China (Grant No IRT0656)the National Natural Science Foundation of China (Grant No 50490270)
文摘Montmorillonite is a kind of clay mineral which often causes large deformation in soft-rock tunnel engineering and thus brings about safety problems in practice.To deal with these engineering safety problems,the physical and chemical properties of montmorillonite should be studied from basic viewpoints.We study the atomic and electronic structures of montmorillonite by using density-functional theory within the local-density approximation （LDA）.The results of calculation show that Al-O bond lengths are longer than Si-O bond lengths.It is found that both the valence band maximum （VBM） and the conduction band minimum （CBM） of montmorillonite are at point Г,and the calculated direct band gap of montmorillonite is 5.35 eV. We show that the chemical bonding between cations and oxygen anions in montmorillonite is mainly ionic,accompanied as well by a minor covalent component.It is pointed out that the VBM and CBM of montmorillonite consist of oxygen 2p and cation s states,respectively.Our calculated results help to understand the chemical and physical properties of montmorillonite,and are expected to be a guide for solving the problem of large deformation of soft-rock tunnels.
