Two new coordination polymers,[Ni(Hpdc)(bib)(H_(2)O)]_(n)(1)and{[Ni(bib)_(3)](ClO_(4))_(2)}_(n)(2),were prepared by mixing Ni^(2+),3,5⁃pyrazoledicarboxylic acid(H3pdc)/p⁃nitrobenzoic acid and 1,4⁃bis(imidazol⁃1⁃ylmeth...Two new coordination polymers,[Ni(Hpdc)(bib)(H_(2)O)]_(n)(1)and{[Ni(bib)_(3)](ClO_(4))_(2)}_(n)(2),were prepared by mixing Ni^(2+),3,5⁃pyrazoledicarboxylic acid(H3pdc)/p⁃nitrobenzoic acid and 1,4⁃bis(imidazol⁃1⁃ylmethyl)butane(bib)by a hydrothermal method,respectively.X⁃ray crystallography reveals a 2D network constructed by six⁃coordinated Ni(Ⅱ)centers,bib,and Hpdc2-ligands in complex 1,while a 2D network is built by Ni(Ⅱ)and bib ligands in 2.Furthermore,the quantum⁃chemical calculations have been performed on‘molecular fragments’extracted from the crystal structure of 1 using the PBE0/LANL2DZ method in Gaussian 16 and the VASP program.CCDC:2343794,1;2343798,2.展开更多
The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the ...The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the first-principles calculation. The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heats of formation and cohesive energies show that Al_2Ca has the strongest alloying ability and structural stability. The densities of states（DOS）, Mulliken electron occupation number, metallicity and charge density difference of these compounds are given. The elastic constants of Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca phases are calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio are derived. The calculations of thermodynamic properties show that the Gibbs free energies of Al_2Ca and Mg_2 Sn are lower than that of Mg_（17）Al_（12）, which indicates that Al_2Ca and Mg_2 Sn are more stable than Mg_（17）Al_（12） phase. Hence, the heat resistance of Mg-Al-based alloys can be improved by adding Ca and Sn additions.展开更多
In order to decrease model complexity of rice panicle for its complicated morphological structure,an interactive L-system based on substructure algorithm was proposed to model rice panicle in this study.Through the an...In order to decrease model complexity of rice panicle for its complicated morphological structure,an interactive L-system based on substructure algorithm was proposed to model rice panicle in this study.Through the analysis of panicle morphology,the geometrical structure models of panicle spikelet,axis and branch were constructed firstly.Based on that,an interactive panicle L-system model was developed by using substructure algorithm to optimize panicle geometrical models with the similar structure.Simulation results showed that the interactive L-system panicle model based on substructure algorithm could fast construct panicle morphological structure in reality.In addition,this method had the well reference value for other plants model research.展开更多
A structure relaxation model based on the empirical electron theory of solids and molecules is developed to compute the diffusion active energies of C, N in γFe. First, adding a restriction, the lattice maintains rig...A structure relaxation model based on the empirical electron theory of solids and molecules is developed to compute the diffusion active energies of C, N in γFe. First, adding a restriction, the lattice maintains rigidity when solute atom migrates to the saddle point. In this step, the hybridization classes of every atom do not change. Then, the restriction is loosed and the atoms are relaxed under the coulomb repulsive forces. It is supposed that the energy needed in the first step would be compensated partly by the second step. In this way, the diffusion active energies of C, N in γFe are computed. Compared with the experiment data, the relative errors are less than 5%, which are good results in the computation of activation energy of diffusion.展开更多
The electronic structures and mechanical properties of Al4Sr, Mg2Sr and Mg23Sr6 phases were determined by the use of first-principles calculations. The calculated heat of formation and cohesive energy indicate that Al...The electronic structures and mechanical properties of Al4Sr, Mg2Sr and Mg23Sr6 phases were determined by the use of first-principles calculations. The calculated heat of formation and cohesive energy indicate that Al4Sr has the strongest alloying ability as well as the highest structural stability. The elastic parameters were calculated, and then the bulk modulus, shear modulus, elastic modulus and Poisson ratio were derived. The ductility and plasticity were discussed. The results show that Al4Sr and Mg2Sr phases both are ductile, on the contrary, Mg23Sr6 is brittle, and among the three phases, Mg2Sr is a phase with the best plasticity.展开更多
The electronic structure,including band structure,density of states （DOS）, and partial density of states of SrTi1-xSbxO3 with x = 0,0. 125,0.25,and 0.33 is calculated from the first principles of plane wave ultra-so...The electronic structure,including band structure,density of states （DOS）, and partial density of states of SrTi1-xSbxO3 with x = 0,0. 125,0.25,and 0.33 is calculated from the first principles of plane wave ultra-soft pseudo-potential technology based on density function theory. The calculated results reveal that due to the electron doping,the Fermi level moves into the conduction bands for SrTi1-xSbxO3 with x = 0. 125 and the system shows metallic behavior. In addition, the DOS moves towards low energy and the optical band gap is broadened. The wide band gap and the low density of the states in the conduction band result in the transparency of the films.展开更多
The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation meth...The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.展开更多
文摘Two new coordination polymers,[Ni(Hpdc)(bib)(H_(2)O)]_(n)(1)and{[Ni(bib)_(3)](ClO_(4))_(2)}_(n)(2),were prepared by mixing Ni^(2+),3,5⁃pyrazoledicarboxylic acid(H3pdc)/p⁃nitrobenzoic acid and 1,4⁃bis(imidazol⁃1⁃ylmethyl)butane(bib)by a hydrothermal method,respectively.X⁃ray crystallography reveals a 2D network constructed by six⁃coordinated Ni(Ⅱ)centers,bib,and Hpdc2-ligands in complex 1,while a 2D network is built by Ni(Ⅱ)and bib ligands in 2.Furthermore,the quantum⁃chemical calculations have been performed on‘molecular fragments’extracted from the crystal structure of 1 using the PBE0/LANL2DZ method in Gaussian 16 and the VASP program.CCDC:2343794,1;2343798,2.
基金Project(20131083) supported by the Doctoral Starting up Foundation of Liaoning Province,ClhinaProject(LT201304) supported by the Program for Liaoning Innovative Research Team in University,ChinaProject(2013201018) supported by the Key Technologies Research and Development Program of Liaoning Province,China
文摘The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the first-principles calculation. The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heats of formation and cohesive energies show that Al_2Ca has the strongest alloying ability and structural stability. The densities of states（DOS）, Mulliken electron occupation number, metallicity and charge density difference of these compounds are given. The elastic constants of Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca phases are calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio are derived. The calculations of thermodynamic properties show that the Gibbs free energies of Al_2Ca and Mg_2 Sn are lower than that of Mg_（17）Al_（12）, which indicates that Al_2Ca and Mg_2 Sn are more stable than Mg_（17）Al_（12） phase. Hence, the heat resistance of Mg-Al-based alloys can be improved by adding Ca and Sn additions.
基金Supported by National Natural Science Foundation of China(60802040)Youth Fund in Southwest University of Science and Technology(10zx3106)~~
文摘In order to decrease model complexity of rice panicle for its complicated morphological structure,an interactive L-system based on substructure algorithm was proposed to model rice panicle in this study.Through the analysis of panicle morphology,the geometrical structure models of panicle spikelet,axis and branch were constructed firstly.Based on that,an interactive panicle L-system model was developed by using substructure algorithm to optimize panicle geometrical models with the similar structure.Simulation results showed that the interactive L-system panicle model based on substructure algorithm could fast construct panicle morphological structure in reality.In addition,this method had the well reference value for other plants model research.
文摘A structure relaxation model based on the empirical electron theory of solids and molecules is developed to compute the diffusion active energies of C, N in γFe. First, adding a restriction, the lattice maintains rigidity when solute atom migrates to the saddle point. In this step, the hybridization classes of every atom do not change. Then, the restriction is loosed and the atoms are relaxed under the coulomb repulsive forces. It is supposed that the energy needed in the first step would be compensated partly by the second step. In this way, the diffusion active energies of C, N in γFe are computed. Compared with the experiment data, the relative errors are less than 5%, which are good results in the computation of activation energy of diffusion.
基金Project (200805321032) supported by Doctoral Fund of Ministry of Education of ChinaProject (51071065) supported by the National Natural Science Foundation of ChinaProject (71075003) supported by the Science Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, China
文摘The electronic structures and mechanical properties of Al4Sr, Mg2Sr and Mg23Sr6 phases were determined by the use of first-principles calculations. The calculated heat of formation and cohesive energy indicate that Al4Sr has the strongest alloying ability as well as the highest structural stability. The elastic parameters were calculated, and then the bulk modulus, shear modulus, elastic modulus and Poisson ratio were derived. The ductility and plasticity were discussed. The results show that Al4Sr and Mg2Sr phases both are ductile, on the contrary, Mg23Sr6 is brittle, and among the three phases, Mg2Sr is a phase with the best plasticity.
文摘The electronic structure,including band structure,density of states （DOS）, and partial density of states of SrTi1-xSbxO3 with x = 0,0. 125,0.25,and 0.33 is calculated from the first principles of plane wave ultra-soft pseudo-potential technology based on density function theory. The calculated results reveal that due to the electron doping,the Fermi level moves into the conduction bands for SrTi1-xSbxO3 with x = 0. 125 and the system shows metallic behavior. In addition, the DOS moves towards low energy and the optical band gap is broadened. The wide band gap and the low density of the states in the conduction band result in the transparency of the films.
文摘The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.
