The possible geometrical and the electronic structures of small MgnNi （n = 1 - 7） clusters are optimised by the density functional theory with a LANL2DZ basis set. The binding energy, the energy gap, the electron af...The possible geometrical and the electronic structures of small MgnNi （n = 1 - 7） clusters are optimised by the density functional theory with a LANL2DZ basis set. The binding energy, the energy gap, the electron affinity, the dissociation energy and the second difference in energy are calculated and discussed. The properties of MgnNi clusters are also discussed when the number of Mg atom increases.展开更多
Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new mater...Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new materials in this respect.In van der Waals(vdW)layered materials,these building blocks are charge neutral and can be isolated from their bulk phase(top-down),but usually grow on substrate.In ionic layered materials,they are charged and usually cannot exist independently but can serve as motifs to construct new materials(bottom-up).In this paper,we introduce our recently constructed databases for 2D material-substrate interface(2DMSI),and 2D charged building blocks.For 2DMSI database,we systematically build a workflow to predict appropriate substrates and their geometries at substrates,and construct the 2DMSI database.For the 2D charged building block database,1208 entries from bulk material database are identified.Information of crystal structure,valence state,source,dimension and so on is provided for each entry with a json format.We also show its application in designing and searching for new functional layered materials.The 2DMSI database,building block database,and designed layered materials are available in Science Data Bank at https://doi.org/10.57760/sciencedb.j00113.00188.展开更多
Employing density functional theory, we study the tensile and fracture processes of the phase interfaces in Mg–Li binary alloy. The simulation presents the strain–stress relationships, the ideal tensile strengths, a...Employing density functional theory, we study the tensile and fracture processes of the phase interfaces in Mg–Li binary alloy. The simulation presents the strain–stress relationships, the ideal tensile strengths, and the fracture processes of three phase interfaces. The results show that the α/α and α/β interfaces have larger tensile strength than that of β/β interface. The fractures of both α/α and β/β interfaces are ductile fractures, while the α/β fractures abruptly._Further analyses show that the fracture of the α/β occurs at the interface.展开更多
The effect of magnesium atom on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtizane(HNIW,CL-20)explosive is considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p).The M...The effect of magnesium atom on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtizane(HNIW,CL-20)explosive is considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p).The Mg atom transfers some electron population to CL-20and one of the nitro groups linked to 6-membered piperazine ring system(base)is expelled in the prenitrite form.The total Mulliken charges on the NO2group reveals that the respective nitramine bond in CL-20is the most susceptible one to impact.The calculated IR and UV-VIS spectra are investigated.The effect of Mg atom on the molecular orbital energies,especially the HOMO and LUMO has been discussed.Narrowing of the interfrontier molecular orbital energy gap(Δε)in the composite system occurs.Therefore,the composite system is more susceptible to impact compared to CL-20.展开更多
Al coating on U surfaces is one of the methods to protect U against environmental corrosion. The behaviors of hydrogen and oxygen impurities near the Al/α-U interface have been studied in the density functional theor...Al coating on U surfaces is one of the methods to protect U against environmental corrosion. The behaviors of hydrogen and oxygen impurities near the Al/α-U interface have been studied in the density functional theory framework. It turns out that U vacancies tend to segregate to the interface with segregation energies of around 0.5-0.8 eV. The segregated U vacancy can act as a sink for H and O impurities, which is saturated when filled with 8 H or 6 O atoms, respectively.Moreover, the O impurities tend to stay in the Al layer while the H impurities prefer to diffuse into the U lattice, suggesting that the Al coating can play a significant role against oxidation but not against hydrogenation of U.展开更多
The stuctures of contact ion pairs of magnesium sulfate were studied. The geometries of contact ion pairs of MgSO 4(H 2O) n (n =1-6) were optimized by using Hartree Fock (HF/6 31+G *, HF/6 311+G ** ) and...The stuctures of contact ion pairs of magnesium sulfate were studied. The geometries of contact ion pairs of MgSO 4(H 2O) n (n =1-6) were optimized by using Hartree Fock (HF/6 31+G *, HF/6 311+G ** ) and density functional theory (DFT) (B3LYP/6 31+G *, B3LYP/6 311+G ** ) methods. The stable structures of monodentate, bidentate and tridentate contact ion pairs were obtained. The bidentate structure of contact ion pairs are the most stable compaired with the monodentate and tridentate ones for the same composition. The hydration enthalpies of contact ion pairs of MgSO 4 (H 2O) n (n =1-4) increase with their hydration numbers.展开更多
Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation kinetics.Graphite anodes adopt different stacking sequences depending on the concentrati...Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation kinetics.Graphite anodes adopt different stacking sequences depending on the concentration of the intercalated Li ions.In this work,we performed first-principles calculations to comprehensively address the energetics and dynamics of Li intercalation and Li vacancy diffusion near the no n-basal edges of graphite,namely the armchair and zigzag-edges,at high Li concentration.We find that surface effects persist in stage-Ⅱ that bind Li strongly at the edge sites.However,the pronounced effect previously identified at the zigzag edge of pristine graphite is reduced in LiC_(12),penetrating only to the subsurface site,and eventually disappearing in LiC_(6).Consequently,the distinctive surface state at the zigzag edge significantly impacts and restrains the charging rate at the initial lithiation of graphite anodes,whilst diminishes with an increasing degree of lithiation.Longer diffusion time for Li hopping to the bulk site from either the zigzag edge or the armchair edge in LiC_(6) was observed during high state of charge due to charge repulsion.Effectively controlling Li occupation and diffusion kinetics at this stage is also crucial for enhancing the charge rate.展开更多
As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO ...As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 10676022)
文摘The possible geometrical and the electronic structures of small MgnNi （n = 1 - 7） clusters are optimised by the density functional theory with a LANL2DZ basis set. The binding energy, the energy gap, the electron affinity, the dissociation energy and the second difference in energy are calculated and discussed. The properties of MgnNi clusters are also discussed when the number of Mg atom increases.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61888102,52272172,and 52102193)the Major Program of the National Natural Science Foundation of China(Grant No.92163206)+2 种基金the National Key Research and Development Program of China(Grant Nos.2021YFA1201501 and 2022YFA1204100)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities.
文摘Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new materials in this respect.In van der Waals(vdW)layered materials,these building blocks are charge neutral and can be isolated from their bulk phase(top-down),but usually grow on substrate.In ionic layered materials,they are charged and usually cannot exist independently but can serve as motifs to construct new materials(bottom-up).In this paper,we introduce our recently constructed databases for 2D material-substrate interface(2DMSI),and 2D charged building blocks.For 2DMSI database,we systematically build a workflow to predict appropriate substrates and their geometries at substrates,and construct the 2DMSI database.For the 2D charged building block database,1208 entries from bulk material database are identified.Information of crystal structure,valence state,source,dimension and so on is provided for each entry with a json format.We also show its application in designing and searching for new functional layered materials.The 2DMSI database,building block database,and designed layered materials are available in Science Data Bank at https://doi.org/10.57760/sciencedb.j00113.00188.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.50874079,51002102,and 61205179)the Natural Science Foundation of Shanxi Province,China(Grant No.2009021026)
文摘Employing density functional theory, we study the tensile and fracture processes of the phase interfaces in Mg–Li binary alloy. The simulation presents the strain–stress relationships, the ideal tensile strengths, and the fracture processes of three phase interfaces. The results show that the α/α and α/β interfaces have larger tensile strength than that of β/β interface. The fractures of both α/α and β/β interfaces are ductile fractures, while the α/β fractures abruptly._Further analyses show that the fracture of the α/β occurs at the interface.
文摘The effect of magnesium atom on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtizane(HNIW,CL-20)explosive is considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p).The Mg atom transfers some electron population to CL-20and one of the nitro groups linked to 6-membered piperazine ring system(base)is expelled in the prenitrite form.The total Mulliken charges on the NO2group reveals that the respective nitramine bond in CL-20is the most susceptible one to impact.The calculated IR and UV-VIS spectra are investigated.The effect of Mg atom on the molecular orbital energies,especially the HOMO and LUMO has been discussed.Narrowing of the interfrontier molecular orbital energy gap(Δε)in the composite system occurs.Therefore,the composite system is more susceptible to impact compared to CL-20.
基金Project supported by Science Challenge Project of China(Grant No.TZ2016002)the National Key R&D Program of China(Grant No.2017YFB0702201)
文摘Al coating on U surfaces is one of the methods to protect U against environmental corrosion. The behaviors of hydrogen and oxygen impurities near the Al/α-U interface have been studied in the density functional theory framework. It turns out that U vacancies tend to segregate to the interface with segregation energies of around 0.5-0.8 eV. The segregated U vacancy can act as a sink for H and O impurities, which is saturated when filled with 8 H or 6 O atoms, respectively.Moreover, the O impurities tend to stay in the Al layer while the H impurities prefer to diffuse into the U lattice, suggesting that the Al coating can play a significant role against oxidation but not against hydrogenation of U.
文摘The stuctures of contact ion pairs of magnesium sulfate were studied. The geometries of contact ion pairs of MgSO 4(H 2O) n (n =1-6) were optimized by using Hartree Fock (HF/6 31+G *, HF/6 311+G ** ) and density functional theory (DFT) (B3LYP/6 31+G *, B3LYP/6 311+G ** ) methods. The stable structures of monodentate, bidentate and tridentate contact ion pairs were obtained. The bidentate structure of contact ion pairs are the most stable compaired with the monodentate and tridentate ones for the same composition. The hydration enthalpies of contact ion pairs of MgSO 4 (H 2O) n (n =1-4) increase with their hydration numbers.
基金financial support from the National Natural Science Foundation of China(52203303)the International Partnership Program of the Chinese Academy of Sciences(321GJHZ2023189FN)+2 种基金the Natural Science Foundation of Guangdong Province(2022A1515010076)the Shenzhen Science and Technology Program(SGDX20211123151002003)the Shenzhen International Cooperation Program(GJHZ20220913142812025)。
文摘Graphite interfaces are an important part of the anode in lithium-ion batteries(LIBs),significantly influencing Li intercalation kinetics.Graphite anodes adopt different stacking sequences depending on the concentration of the intercalated Li ions.In this work,we performed first-principles calculations to comprehensively address the energetics and dynamics of Li intercalation and Li vacancy diffusion near the no n-basal edges of graphite,namely the armchair and zigzag-edges,at high Li concentration.We find that surface effects persist in stage-Ⅱ that bind Li strongly at the edge sites.However,the pronounced effect previously identified at the zigzag edge of pristine graphite is reduced in LiC_(12),penetrating only to the subsurface site,and eventually disappearing in LiC_(6).Consequently,the distinctive surface state at the zigzag edge significantly impacts and restrains the charging rate at the initial lithiation of graphite anodes,whilst diminishes with an increasing degree of lithiation.Longer diffusion time for Li hopping to the bulk site from either the zigzag edge or the armchair edge in LiC_(6) was observed during high state of charge due to charge repulsion.Effectively controlling Li occupation and diffusion kinetics at this stage is also crucial for enhancing the charge rate.
基金supported by the National Natural Science Foundation of China (Grants No. 11234013)“863” Project (Grant No. 2015AA034201)+1 种基金Beijing S&T Project (Grant No. D161100002416003)Youth Innovation Promotion Association (Grant No. 2016005) for financial support and the Shanghai Supercomputer Center for providing computing resources
基金supported by the Petro China Innovation Foundation,China(2015D-5006-0213)Fundamental Research Funds for the Central Universities,China(14CX02221A,14CX06157A)~~
基金supported by the National Natural Science Foundation of China(22178388,21776315)the Taishan Scholars Program of Shandong Province(tsqn201909065)the Fundamental Research Funds for the Central Universities(19CX05001A).
文摘As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.
