We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energ...We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energy profile was plotted. The properties of the bonds of all special structures in the reaction path were analyzed using the method of the electron localization function (ELF). The results indicate that the final reaction pathway can be expressed as Ce+O2→ FC→TS→IM→O-Ce-O, and the formation of Ce2O3 has not been found. In addition, the ELF diagram of the final product CeO2 shows that Ce bonds with both O atoms and the bond angles increase significantly.展开更多
Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different r...Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different reaction products is presented.We report a complete exploration of the potential energy surfaces by taking into consideration different spin states.In addition,the intermediate and transition states along the reaction paths are characterized.Total,partial,and overlap population density of state diagrams and analyses are also presented.Furthermore,the natures of the chemical bonding of intermediate and transition states are studied by using topological method combined with electron localization function（ELF） and Mayer bond order.Infrared spectrum（IR） is obtained and further discussed based on the optimized geometries.展开更多
Metal-phthalocyanine-based covalent organic frameworks(MPc COFs)could be used to construct fullyπ-conjugated systems.MPcs linked via the-CuC-group are ideal two-dimensional(2D)monolayer networks.The 2Dπ-conjugated s...Metal-phthalocyanine-based covalent organic frameworks(MPc COFs)could be used to construct fullyπ-conjugated systems.MPcs linked via the-CuC-group are ideal two-dimensional(2D)monolayer networks.The 2Dπ-conjugated systems would be beneficial for photo-/electrocatalysis.Herein,we generally performed theoretical calculations on the electronic structures of 2D MPc(M=Ti,Mn,Fe,Co,Ni,Cu,and Zn)COFs linked via the-CuC-moiety.The FePc and CoPc COFs possess higher catalytic activity than the others.ELF(electron localization function)and COHP(crystal orbital Hamilton population)analyses reveal that the isoindole rings in the Pc moiety allow electron conduction,which enhances the charge transfer inside Pc and also the electron transfer between the unit cells of the MPc COFs.Thus,Pc is a good substrate for metal-based active site-catalyzed reactions.展开更多
The structure and stability of the compounds MRg^(+)and MRg F(Rg=Ar,Kr,and Xe;M=Co,Rh,and Ir)were investigated using the B3 LYP,MP2,MP4(SDQ)and CCSD(T)methods.We reported the geometry,vibrational frequencies and therm...The structure and stability of the compounds MRg^(+)and MRg F(Rg=Ar,Kr,and Xe;M=Co,Rh,and Ir)were investigated using the B3 LYP,MP2,MP4(SDQ)and CCSD(T)methods.We reported the geometry,vibrational frequencies and thermodynamics properties of these compounds.A series of theoretical methods on the basis of wavefunction analysis,including natural bond orbitals,atoms in molecules,electron localization function,and energy decomposition analysis,were performed to explore bonding nature of the M-Rg and Rg-F bonds.These bonds are mainly noncovalent,the metal weakly interacts with Rg in MRg^(+),but their interaction is much stronger in MRg F.The neutral molecule MRg F can be well described by the Lewis structure[MRg]^(+)F^(-).展开更多
The nature of the Ga-Ga bonding in Na2[Arx＊GaGaArx＊] （Arx＊ = C6H3-2,6-（C6Hs）2） has been investigated and compared with that of in Hz[Arx＊GaGaArx＊] using electron localization function （ELF） and orbital anal...The nature of the Ga-Ga bonding in Na2[Arx＊GaGaArx＊] （Arx＊ = C6H3-2,6-（C6Hs）2） has been investigated and compared with that of in Hz[Arx＊GaGaArx＊] using electron localization function （ELF） and orbital analysis. The calculation results show that in Na2[Arx＊GaGaArx＊], the Ga-Ga interaction is a non-classical triple bond, the heart of Na2[Arx＊GaGaArx＊] is the Ga2Na2 cluster rather than a simple Ga-Ga bond, and the contribution of the sodium atoms to the short Ga-Ga bond length is considerable. As the two sodium atoms are substituted by two hydrogen atoms, the Ga-Ga bond is replaced by two 3-center, 2-electron （3c-2e） Ga-H-Ga covalent bridged bonding.展开更多
Two new pentanary sulfides Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)(1)and BaLa_(3)GaSb_(2)S_(10)(2)have been discovered by high temperature solid state reactions.Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)features a new zero-dimensional str...Two new pentanary sulfides Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)(1)and BaLa_(3)GaSb_(2)S_(10)(2)have been discovered by high temperature solid state reactions.Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)features a new zero-dimensional structure type,which consists of unique isolated Sb_(2)S_(7)dimers and GaS_(4)tetrahedra.In contrast,with less GaS_(4)tetrahedra in the formula,BaLa_(3)GaSb_(2)S_(10)forms a one-dimensional structure which is constructed by teeter-totter(SbS_(4))n chains and isolated GaS_(4)tetrahedra.On the basis of UV/Vis spectroscopy,their band gaps are determined to be 2.42 and 2.15 eV,respectively,which are much wider than that of analogue La_(4)FeSb_(2)S_(10)(1.0 eV).In addition,theoretical studies illustrate the important role of Ga in expanding the band gaps with respect to Fe atoms.The calculated crystal orbital Hamilton population and electron localization function confirm that the long Sb-S bonds in Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)(2.932(2)A)and BaLa_(3)GaSb_(2)S_(10)(3.216(5)and 3.219(5)A)have weak but nonnegligible bonding interactions.展开更多
Novel Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.8)ceramics,designed by replacing Ce^(4+)with Yb^(3+)ions were prepared by conventional oxide reaction,and the structural stability of the cubic fluorite structure was assessed usin...Novel Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.8)ceramics,designed by replacing Ce^(4+)with Yb^(3+)ions were prepared by conventional oxide reaction,and the structural stability of the cubic fluorite structure was assessed using lattice energy and ionic properties of Ce/Yb-O bonds.The oxygen vacancy caused by unequal substitution,which played a decisive role in bond ionicity and lattice energy,was analyzed experimentally by XPS and also theoretically by first principles.The Yb_(x)Ce_(1-x)O_(2-0.5x) ceramics maintain a stable cubic fluorite structure when x≤0.47,corresponding to the minimum lattice energy of 4142 kJ/mol with the lowest ionicity as ƒ_(i)=87.57%.For microwave dielectric properties,when the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.4)ceramics are pure phase,the porosity-corrected permittivity is dependent on the bond ionicity.The Q׃ values are related to the lattice energy and grain distribution.The temperature coefficient of resonance frequency has been analyzed using bond valence.When the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0.5-0.8)ceramics are multiple phases,the microwave dielectric properties are associated with the phase composition and grain growth.展开更多
文摘We obtained the reaction mechanism of cerium with oxygen by means of density functional theory (DFT) under the explosive or detonation situation. The energy level order of cerium was calculated and the potential energy profile was plotted. The properties of the bonds of all special structures in the reaction path were analyzed using the method of the electron localization function (ELF). The results indicate that the final reaction pathway can be expressed as Ce+O2→ FC→TS→IM→O-Ce-O, and the formation of Ce2O3 has not been found. In addition, the ELF diagram of the final product CeO2 shows that Ce bonds with both O atoms and the bond angles increase significantly.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21371160,21401173,and 11364023)
文摘Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different reaction products is presented.We report a complete exploration of the potential energy surfaces by taking into consideration different spin states.In addition,the intermediate and transition states along the reaction paths are characterized.Total,partial,and overlap population density of state diagrams and analyses are also presented.Furthermore,the natures of the chemical bonding of intermediate and transition states are studied by using topological method combined with electron localization function（ELF） and Mayer bond order.Infrared spectrum（IR） is obtained and further discussed based on the optimized geometries.
基金funded by the National Key Research and Development Program of China(2020YFA0406202)the Natural Science Foundation of China,grant no.22008006,22090042,and 21731001the Fundamental Research Funds for the Central Universities,grant no.FRF-IDRY-20-005 and FRF-TP-20-077A1.
文摘Metal-phthalocyanine-based covalent organic frameworks(MPc COFs)could be used to construct fullyπ-conjugated systems.MPcs linked via the-CuC-group are ideal two-dimensional(2D)monolayer networks.The 2Dπ-conjugated systems would be beneficial for photo-/electrocatalysis.Herein,we generally performed theoretical calculations on the electronic structures of 2D MPc(M=Ti,Mn,Fe,Co,Ni,Cu,and Zn)COFs linked via the-CuC-moiety.The FePc and CoPc COFs possess higher catalytic activity than the others.ELF(electron localization function)and COHP(crystal orbital Hamilton population)analyses reveal that the isoindole rings in the Pc moiety allow electron conduction,which enhances the charge transfer inside Pc and also the electron transfer between the unit cells of the MPc COFs.Thus,Pc is a good substrate for metal-based active site-catalyzed reactions.
文摘The structure and stability of the compounds MRg^(+)and MRg F(Rg=Ar,Kr,and Xe;M=Co,Rh,and Ir)were investigated using the B3 LYP,MP2,MP4(SDQ)and CCSD(T)methods.We reported the geometry,vibrational frequencies and thermodynamics properties of these compounds.A series of theoretical methods on the basis of wavefunction analysis,including natural bond orbitals,atoms in molecules,electron localization function,and energy decomposition analysis,were performed to explore bonding nature of the M-Rg and Rg-F bonds.These bonds are mainly noncovalent,the metal weakly interacts with Rg in MRg^(+),but their interaction is much stronger in MRg F.The neutral molecule MRg F can be well described by the Lewis structure[MRg]^(+)F^(-).
基金supported by the National Natural Science Foundation of China (20973053, 21073051, 21102033, 21171047)the Natural Science Foundation of Hebei Province (B2010000371,B2011205058,B2010000368)the Education Department Foundation of Hebei Province (ZD2010126)
文摘The nature of the Ga-Ga bonding in Na2[Arx＊GaGaArx＊] （Arx＊ = C6H3-2,6-（C6Hs）2） has been investigated and compared with that of in Hz[Arx＊GaGaArx＊] using electron localization function （ELF） and orbital analysis. The calculation results show that in Na2[Arx＊GaGaArx＊], the Ga-Ga interaction is a non-classical triple bond, the heart of Na2[Arx＊GaGaArx＊] is the Ga2Na2 cluster rather than a simple Ga-Ga bond, and the contribution of the sodium atoms to the short Ga-Ga bond length is considerable. As the two sodium atoms are substituted by two hydrogen atoms, the Ga-Ga bond is replaced by two 3-center, 2-electron （3c-2e） Ga-H-Ga covalent bridged bonding.
基金supported by the NSF of China(No.21225104,21233009,91422303,21571020,21301175,21171168 and 21671023)。
文摘Two new pentanary sulfides Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)(1)and BaLa_(3)GaSb_(2)S_(10)(2)have been discovered by high temperature solid state reactions.Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)features a new zero-dimensional structure type,which consists of unique isolated Sb_(2)S_(7)dimers and GaS_(4)tetrahedra.In contrast,with less GaS_(4)tetrahedra in the formula,BaLa_(3)GaSb_(2)S_(10)forms a one-dimensional structure which is constructed by teeter-totter(SbS_(4))n chains and isolated GaS_(4)tetrahedra.On the basis of UV/Vis spectroscopy,their band gaps are determined to be 2.42 and 2.15 eV,respectively,which are much wider than that of analogue La_(4)FeSb_(2)S_(10)(1.0 eV).In addition,theoretical studies illustrate the important role of Ga in expanding the band gaps with respect to Fe atoms.The calculated crystal orbital Hamilton population and electron localization function confirm that the long Sb-S bonds in Ba_(3)La_(4)Ga_(2)Sb_(2)S_(15)(2.932(2)A)and BaLa_(3)GaSb_(2)S_(10)(3.216(5)and 3.219(5)A)have weak but nonnegligible bonding interactions.
基金the Fundamental Research Funds for the Central Universities(Grant No.2020ZDPYMS12).
文摘Novel Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.8)ceramics,designed by replacing Ce^(4+)with Yb^(3+)ions were prepared by conventional oxide reaction,and the structural stability of the cubic fluorite structure was assessed using lattice energy and ionic properties of Ce/Yb-O bonds.The oxygen vacancy caused by unequal substitution,which played a decisive role in bond ionicity and lattice energy,was analyzed experimentally by XPS and also theoretically by first principles.The Yb_(x)Ce_(1-x)O_(2-0.5x) ceramics maintain a stable cubic fluorite structure when x≤0.47,corresponding to the minimum lattice energy of 4142 kJ/mol with the lowest ionicity as ƒ_(i)=87.57%.For microwave dielectric properties,when the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0-0.4)ceramics are pure phase,the porosity-corrected permittivity is dependent on the bond ionicity.The Q׃ values are related to the lattice energy and grain distribution.The temperature coefficient of resonance frequency has been analyzed using bond valence.When the Yb_(x)Ce_(1-x)O_(2-0.5x)(x=0.5-0.8)ceramics are multiple phases,the microwave dielectric properties are associated with the phase composition and grain growth.
