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ab initio calculations of the Electronic Structures of Copper Pyrites CuS2, CuSe2 and CuTe2

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Journal of Materials Science & Technology 2004年第4期20卷 429-431页

作者： Zhufeng HOU, Aiyu LI, Zizhong ZHU and Meichun HUANGDepartment of Physics, Xiamen University, Fujian 361005, China Dept. of Phys. Xiamen Univ. Xiamen 361005 China

The electronic structures of CuS2, CuSe2 and CuTe2 with pyrite structures, within the framework the density-functional theory have been investigated. The calculated results explained the recent experimental results which show that there is no clear indication of strong electron correlations in the electronic properties of Cu pyrites, due to the dominant chalcogen p character rather than d characteristic of Cu at the Fermi level.

关键词： ab initio calculations Copper pyrites Electronic structures

Rotational Isomeric State Model of Poly(vinylidene chloride) Based Upon ab initio Electronic Structure calculations

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Chemical Research in Chinese Universities 2009年第1期25卷 108-111页

作者： ZHANG Zhi-jie LIU Yu-hua Lü Zhong-yuan LI Ze-sheng Institute of Theoretical Chemistry State Key Laboratory of Theoretical and Computational Chemistry Jilin University Changchun 130021 P. R. China

The rotational isomeric state（RIS） model was constructed for poly（vinylidene chloride）（PVDC） based on quantum chemistry calculations. The statistical weighted parameters were obtained from RIS representations and ab initio energies of conformers for model molecules 2,2,4,4-tetrachloropentane（TCP） and 2,2,4,4,6, 6-hexachloroheptane（HCH）. By employing the RIS method, the characteristic ratio C∞ was calculated for PVDC. The calculated characteristic ratio for PVDC is in good agreement with experiment result. Additionally, we studied the influence of the statistical weighted parameters on C∞ by calculating δC∞/δlnw. According to the values of δC∞/δlnw, the effects of second-order Cl-CH2 pentane type interaction and C1--C1 long range interaction on C∞ were found to be important. In contrast, first-order interaction is unimportant.

关键词： ab initio calculations Characteristic ratio Poly（vinylidene chloride）

Nuclear volume effects in kinetic isotope fractionation:A case study of mercury oxidation by chlorine species

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Acta Geochimica 2024年第3期43卷 411-423页

作者： Chenlu Yang Yining Zhang Yun Liu Research Center for Planetary Science College of Earth and Planetary SciencesChengdu University of TechnologyChengdu 610059China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

It is well-known that the equilibrium isotope fractionation of mercury(Hg)includes classical massdependent fractionations(MDFs)and nuclear volume effect(NVE)induced mass-independent fractionations(MIFs).However,the effect of the NVE on these kinetic processes is not known.The total fractionations(MDFs+NVEinduced MIFs)of several representative Hg-incorporated substances were selected and calculated with ab initio calculations in this work for both equilibrium and kinetic processes.NVE-induced MIFs were calculated with scaled contact electron densities at the nucleus through systematic evaluations of their accuracy and errors using the Gaussian09 and DIRAC19 packages(named the electron density scaling method).Additionally,the NVE-induced kinetic isotope effect(KIE)of Hg isotopes are also calculated with this method for several representative Hg oxidation reactions by chlorine species.Total KIEs for 202 Hg/^(198)Hg ranging from−2.27‰to 0.96‰are obtained.Three anomalous^(202)Hg-enriched KIEs(δ^(202)Hg/^(198)Hg=0.83‰,0.94‰,and 0.96‰,)caused by the NVE are observed,which are quite different from the classical view(i.e.,light isotopes react faster than the heavy ones).The electron density scaling method we developed in this study can provide an easier way to calculate the NVE-induced KIEs for heavy isotopes and serve to better understand the fractionation mechanisms of mercury isotope systems.

关键词： Nuclear volume effect Kinetic fractionation Hg isotopes ab initio calculations

Elucidating elusive quaternary selenide EuCeCuSe3:Synthesis,crystal structure,properties and theoretical studies

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Journal of Rare Earths 2024年第1期42卷 163-171,I0006页

作者： Maxim V.Grigoriev Anna V.Ruseikina Maxim S.Molokeev Vladimir A.Chernyshev Aleksandr S.Aleksandrovsky Alexander S.Krylov Svetlana N.Krylova Nikolai P.Shestakov Dmitriy A.Velikanov Alexander A.Garmonov Alexey V.Matigorov Evgeny A.Ostapchuk Thomas Schleid Damir A.Safin Laboratory of Theory and Optimization of Chemical and Technological Processes University of TyumenVolodarskogo Str.6625003TyumenRussian Federation Kirensky Institute of Physics Federal Research Center KSC SB RASAkademgorodok 50 Bld.38660036KrasnoyarskRussian Federation Department of Physics Far Eastern State Transport UniversitySerysheva Str.47680021KrasnoyarskRussian Federation Institute of Natural Sciences and Mathematics Ural Federal University Named After the First President of Russia B.N.YeltsinMira Str.19620002EkaterinburgRussian Federation Department of Photonics and Laser Technology Siberian Federal UniversitySvobodnii Ave.79660079KrasnoyarskRussian Federation Institute of Physics and Technology University of TyumenVolodarskogo Str.6625003 TyumenRussian Federation Institute for Inorganic Chemistry University of StuttgartPfaffenwaldring 55D-70569StuttgartGermany Scientific and Educational and Innovation Center for Chemical and Pharmaceutical Technologies Ural Federal University named after the First President of Russia B.N.YeltsinMira Str.19620002 EkaterinburgRussian Federation University of Tyumen Volodarskogo Str.6625003TyumenRussian Federation

We report on the novel heterometallic quaternary selenide EuCeCuSe3,the fabrication of which has been a challenge until this work.The structure of the reported selenide was elucidated from the powder X-ray diffraction data,which revealed the formation of EuCeCuSe3with excellent yield(96.7%)accompanied with a minor fraction of CeSe2(3.3%),and was best solved in orthorhombic space group Pnma with the BaLaCuS3structural type.Thus,the crystal structure of the title compound completes the row of the heterometallic quaternary selenides EuRECuSe3(RE=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Y),of which the cerium-based derivative exclusively belongs to the BaLaCuS3structural type.The distortion of the CuSe4polyhedron was compared for the whole series of EuRECuSe3compounds using theτ4-descriptor for four coordinated ions,which revealed the highest degree of distortion for the Ce3+-containing selenide,followed by the La3+-based derivative.Furthermore,the crystallographic and geometrical parameters of the reported selenide were discussed in comparison to the Ce3+-based sulfides SrCeCuS3and EuCeCuS3.ab initio calculations of the crystal structure,a phonon spectrum and elastic constants for the crystal of EuCeCuSe3were also performed.The types and wavenumbers of fundame ntal modes were determined and the involvement of ions participating in the phonon modes was assessed.The experimental IR spectrum of the reported selenide was interpreted and found to be in agreement with the calculated spectrum.The experimental direct band gap of EuCeCuSe3was measured to be 1.36 eV that is consistent with the concept of its origin due to interband transitions between orbitals emerging mainly from 4f(valence band)and 5d(conduction band)levels of the Eu2+cation.The dependence of the Young’s modulus on the direction demonstrates the anisotropy of the elastic properties,while the Vickers hardness for EuCeCuSe3was calculated to be 5.2 GPa.Finally,the title compound is paramagnetic above 4 K.

关键词： Quaternary selenide Synthesis Crystal structure ab initio calculations Magnetic measurements Spectroscopy

Strong Antiferromagnetic Exchange-Coupling Observed in Hydride-Bridged Dimeric Dysprosium(Ⅲ)Single-Molecule Magnet

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Chinese Journal of Chemistry 2024年第4期42卷 391-396页

作者： Qian-Cheng Luo Ke-Xin Yu Peng-Bo Jin Ye-Ye Liu Yuan-Qi Zhai Yan-Zhen Zheng Frontier Institute of Science and Technology State Key Laboratory of Electrical Insulation and Power EquipmentXi'an Key Laboratory of Electronic Devices and Materials ChemistrySchool of Chemistry and School of PhysicsXi'an Jiaotong University99 Yanxiang RoadXi'anShaanxi710054 China

One dihydride-bridged dimeric Dy(Ⅲ)guanidinate complex,formulated as[{(Me_(3)Si)_(2)NC(NiPr)_(2)}_(2)Dy(μ-H)]_(2)(1Dy),was successfully isolated and the introduction of hydride bridges significantly reduces the intramolecular Dy(Ⅲ)…Dy(Ⅲ)distance to only 3.688(1)Å.To investigate the effect of such a short Dy(Ⅲ)…Dy(Ⅲ)distance on magnetism,we also prepared its dibromide-bridged analogue[{(Me_(3)Si)_(2)NC(NiPr)_(2)}_(2)Dy(μ-Br)]_(2)(2Dy),which has a much longer Dy(Ⅲ)…Dy(Ⅲ)distance of 4.605(4)Å.Surprisingly,2Dy demonstrates much larger effective energy barrier for magnetization reversal(U_(eff))and higher blocking temperature(T_(B)).The worse performance of 1Dy is attributed to the concerted effect of strong antiferromagnetic interactions between Dy(Ⅲ)ions(J_(total)=–2.683 cm^(–1))and the unparallel arrangement of magnetic principle axes of the Dy(Ⅲ)ions for 1Dy.

关键词： Single-molecule magnets Lanthanides Guanidinate ligand Hydride bridge Magnetic properties ab initio calculations

Electronic structure of the rare-earth superstoichiometric dihydride GdH_(2.25)

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Rare Metals 2022年第8期41卷 2794-2799页

作者： Zahia Ayat Aomar Boukraa abdelouahab Ouahab Bahmed Daoudi Fac.Des Mathématiques et des Sciences de la Matière Lab.Développement desénergies nouvelles et renouvelables dans les zones arides et sahariennesUniversity of Ouargla30000OuarglaAlgeria Département des Sciences de la Matière Facultédes Sciences Exactes et des Sciences de la Nature et de la VieUniversitéMohamed Khider Biskra07000BiskraAlgeria

With the WIEN2 k simulation code,ab initio calculations of electronic structure and of equilibrium properties for the superstoichiometric rare-earth dihydride GdH_(2.25)using the full-potential linearized augmented plane-wave(FP-LAPW)method within density functional theory(DFT)in generalized gradient approximation(GGA)were performed.The lattice parameter,bulk modulus,pressure derivative,density of states(DOS)and energy band structures were determined.The GGA-optimized lattice parameter agrees much better with the experimental findings than the local density approximation(LDA)one.The non-negligible electronic DOS at Fermi level confirms that GdH_(2.25)has a metallic character.The Fermi energy(E_(F))falls at a level where most of the states are rare-earth 5 d conduction states while negligible contributions of both interstitial(tetrahedral and octahedral)H s states are observed near EF.It is found that hybridization exists between s electronic orbital of both interstitial H atoms and d electronic orbitals of Gd.

关键词： Rare-earth dihydrides GdH_(2.25) Density functional theory ab initio calculations WIEN2k

ab initio Investigations for the Role of Compositional Complexities in Affecting Hydrogen Trapping and Hydrogen Embrittlement:A Review

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1159-1172页

作者： Boning Zhang Yong Mao Zhenbao Liu Jianxiong Liang Jun Zhang Maoqiu Wang Jie Su Kun Shen Advanced Computing Center School of Materials and EnergyYunnan UniversityKunming650091China Institute for Special Steel Research Central Iron and Steel Research InstituteBeijing100081China Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China School of Science China University of GeosciencesBeijing100083China

ydrogen embrittlement(HE)seriously restricts the service safety of structural metallic materials applicate in aerospace,ocean,and transportation.Recent studies aiming at increasing the HE-resistance have been focusing on trapping diffusible H atoms by inherent microstructural features in materials.Alloying-induced compositional complexities,including different types of solute atoms,lattice chemical heterogeneities,and carbide precipitates,have attracted research efforts regarding the H trapping capabilities and potential to reduce the susceptibility to HE.In this paper,we review recent progress in exploiting compositional complexities to regulate the hydrogen trapping characteristics and mechanical properties in H-containing environments.The focus is placed on results and insights from ab initio calculations based on density functional theory(DFT).Quantitative predictions of trapping parameters and atomic scale details that are hardly to be gained through traditional experimental characterizations are provided.Additionally,we overview the electronic/atomistic mechanisms of H trapping energetics in metallic materials.Finally,we propose some key challenges and prospects in simulation of defect interactions,interpretation of experimental characterizations,and developing microstructure-based H diffusion prediction models.For the applications of first principle calculations,we illustrate how the DFT data can complement experimental characterizations to guide composition and microstructure design for better HE-resistant materials.

关键词： ab initio calculations Hydrogen trapping Hydrogen embrittlement Precipitation Composition design

Trinuclear Dy(III)Single-Molecule Magnets with Two-Step Relaxation

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Chinese Journal of Chemistry 2023年第20期41卷 2641-2647页

作者： Yi-Shu Jin Cai-Ming Liu Yi-Quan Zhang Hui-Zhong Kou Engineering Research Center of Advanced Rare Earth Materials(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing100084 China Beijing National Laboratory for Molecular Sciences Center for Molecular ScienceInstitute of ChemistryChinese Academy of SciencesBeijing100190 China Jiangsu Key Lab for NSLSCS School of Physical Science and TechnologyNanjing Normal UniversityNanjingJiangsu210023 China

The reaction of DyCl_(3)·6H_(2)O with a rigid diacylhydrazone ligand(H_(2)L)afforded a trinuclear precursor[Dy_(3)L_(2)Cl_(3)(H_(2)O)_(2)(CH_(3)OH)]Cl_(2)·3CH_(3)OH(1).The replacement of the Cl-ions and the coordinating solvents by the aryloxides ligands(Lx)-yields three trinuclear complexes[Dy_(3)L_(2)(Lx)_(5)]·nsol(x=1,2-naphthol(2);x=2,7-hydroxycoumarin(3);and x=3,phenol(4)).In complexes 2-4,two end Dy^(3+)centers adopt almost identical N_(4)O_(4) coordination sphere of D6h geometry while the central one adopts N_(4)O_(5) coordination sphere in Cs geometry.Magnetic measurements reveal weak antiferromagnetic interactions in the hydrated samples 2e-4e and two-step slow relaxation process under zero dc field with effective energy barriers Ueff of 439 and 91 K,353 and 40 K,466 and 89 K for SR and FR in 2e-4e,respectively.Such dynamic magnetic behaviour for 4 persists in the magnetically diluted sample of 4@Y.Complex 4 possesses the short Dy-O_(aryloxide) bond distance of 2.055(18)Å,and the largest Ueff among the reported linear trinuclear dysprosium complexes.Moreover,the functionalized aryloxides ligands(Lx)-show photoluminescence via intramolecular energy transfer,making 2e-4e luminescent Dy^(3+)SMMs with high energy barriers.

关键词： Coordination modes Lanthanides Crystal structure ab initio calculations Magnetic properties Luminescence

Dramatic Impact of Auxiliary Ligands on the Dynamic Magnetic Relaxation in Tetranuclear Dy^(III)_(2)Zn^(II)_(2) Single Molecule Magnets

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Chinese Journal of Chemistry 2022年第20期40卷 2415-2420页

作者： Gao-Peng Li Hong-Fang Xie Shi-Rui Yang Yun-Long Fu Yi-Quan Zhang Yao-Yu Wang Key Laboratory of Magnetic Molecules&Magnetic Information Materials of the Ministry of Education School of Chemistry&Material ScienceShanxi Normal UniversityTaiyuanShanxi030031 China Weinan Bureau of Natural Resources and Planning WeinanShaanxi714000 China Jiangsu Key Laboratory for NSLSCS School of Physical Science and TechnologyNanjing Normal UniversityNanjingJiangsu210023 China Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education Shaanxi Key Laboratory of Physico-Inorganic ChemistryCollege of Chemistry and Materials ScienceNorthwest UniversityXi'anShaanxi710127 China

Better understanding the determining factors of dynamic magnetic relaxation in polynuclear lanthanide based single-molecule magnets(SMMs)remains a challenge due to the complexity of such architectures involving interactions between the magnetic centers.To address this issue,two structurally related heterometal Dy^(III)_(2)Zn^(II)_(2) SMMs,[Zn_(2)Dy_(2)(L)_(4)(Ac)_(2)(DMF)(CH_(3)OH)]·CH_(3)OH·2H_(2)O(1)and[Zn_(2)Dy_(2)(L)_(4)(Ac)_(2)(DMF)_(2)]·4CH_(3)CN(2)(H_(2)L=(E)-2-((2-hydroxy-3-methoxybenzylidene)amino)-4-methyphenol,DMF=N,N-dimethylformamide),are introduced and investigated.Through modifying the auxiliary ligands on one Dy^(III) site while retaining that on the other Dy^(III),the intramolecular magnetic interactions and relaxation dynamics in these two heterometallic-Dy^(III)_(2)Zn^(II)_(2) SMMs can be tuned,demonstrating a dramatic change in the magnet relaxation behavior with energy barrier changing from a negligible value for 1 to 305 K for 2.ab initio calculations reveal that changing the coordination geometries on the Dy^(III) sites can significantly affect the magnetic interactions as well as single-ion anisotropy.

关键词： Single-molecule magnets Dynamic magnetic relaxation Dysprosium Auxiliary ligands ab initio calculations