The first-principle calculations are performed to investigate the structural,mechanical and electronic properties of titanium borides （Ti2B,TiB and TiB2）.Those calculated lattice parameters are in good agreement wit...The first-principle calculations are performed to investigate the structural,mechanical and electronic properties of titanium borides （Ti2B,TiB and TiB2）.Those calculated lattice parameters are in good agreement with the experimental data and previous theoretical values.All these borides are found to be mechanically stable at ambient pressure.Compared with parent metal Ti （120 GPa）,the larger bulk modulus of these borides increase successively with the increase of the boron content in three borides,which may be due to direction bonding introduced by the boron atoms in the lattice and the strong covalent Ti-B bonds.Additionally,TiB can be regarded as a candidate of incompressible and hard material besides TiB2.Furthermore,the elastic anisotropy and Debye temperatures are also discussed by investigating the elastic constants and moduli.Electronic density of states and atomic Mulliken charges analysis show that chemical bonding in these titanium borides is a complex mixture of covalent,ionic,and metallic characters.展开更多
Within the framework of the embedded-atom method, we performed molecular-dynamics calculations to investigate the structural transformation during melting of two copper clus- ters containing 57 and 58 atoms. The simul...Within the framework of the embedded-atom method, we performed molecular-dynamics calculations to investigate the structural transformation during melting of two copper clus- ters containing 57 and 58 atoms. The simulation results reveal how their different structural changes can strongly influence internal energy and radial distribution functions. The local structural patterns of different regions during the temperature increase, determined by atom density profiles, are identified for the melting of each cluster. The simulations show sensi- tivities of the structural changes for these two small size clusters with different structures.展开更多
Eye observation was used to evaluate the segregation degree of asphalt pavement, which was not much creditable. To the asphalt pavement, road surface texture measuring method which has appeared recently can identify g...Eye observation was used to evaluate the segregation degree of asphalt pavement, which was not much creditable. To the asphalt pavement, road surface texture measuring method which has appeared recently can identify gradational segregation; but it can’t reflect the influence of the temperature segregation. However, using infrared temperature detector to evaluate the segregation must be taken during paving, which brings much inconvenience. In this paper, measuring the air voids distribution using non-nuclear density gauge to evaluate asphalt pavement segregation was introduced. Result shows that this method can directly reflect the comprehensive results of the two types of segregation in a high efficient and accurate way. Moreover, using the sketch map of segregation area can help to analyze the segregation reason visually.展开更多
A recently developed B-spline algorithm is extended and utilized to calculate excited states of He atoms in the presence of strong magnetic fields.Binding energies are presented for He in the five excited atomic state...A recently developed B-spline algorithm is extended and utilized to calculate excited states of He atoms in the presence of strong magnetic fields.Binding energies are presented for He in the five excited atomic states 210-+,110-,210-,11(-1)+,and 2 1(1) + with magnetic field strength ranging from 0.0001 to 10 a.u.The obtained energies are compared with available theoretical data,and found to be in good agreement.We investigate influence of magnetic fields on atomic structures of multielectron atoms,and illustrate that how electron probability density distributions change with increasing magnetic field strength.The current approach is directly applicable to simulations of discrete spectra for He atoms in the atmospheres of magnetized white dwarf stars.展开更多
基金Project(2010JK404) supported by the Education Committee Natural Science Foundation of Shaanxi Province,ChinaProjects(ZK0918,ZK0915) supported by the Baoji University of Arts and Sciences Key Research,China
文摘The first-principle calculations are performed to investigate the structural,mechanical and electronic properties of titanium borides （Ti2B,TiB and TiB2）.Those calculated lattice parameters are in good agreement with the experimental data and previous theoretical values.All these borides are found to be mechanically stable at ambient pressure.Compared with parent metal Ti （120 GPa）,the larger bulk modulus of these borides increase successively with the increase of the boron content in three borides,which may be due to direction bonding introduced by the boron atoms in the lattice and the strong covalent Ti-B bonds.Additionally,TiB can be regarded as a candidate of incompressible and hard material besides TiB2.Furthermore,the elastic anisotropy and Debye temperatures are also discussed by investigating the elastic constants and moduli.Electronic density of states and atomic Mulliken charges analysis show that chemical bonding in these titanium borides is a complex mixture of covalent,ionic,and metallic characters.
文摘Within the framework of the embedded-atom method, we performed molecular-dynamics calculations to investigate the structural transformation during melting of two copper clus- ters containing 57 and 58 atoms. The simulation results reveal how their different structural changes can strongly influence internal energy and radial distribution functions. The local structural patterns of different regions during the temperature increase, determined by atom density profiles, are identified for the melting of each cluster. The simulations show sensi- tivities of the structural changes for these two small size clusters with different structures.
文摘Eye observation was used to evaluate the segregation degree of asphalt pavement, which was not much creditable. To the asphalt pavement, road surface texture measuring method which has appeared recently can identify gradational segregation; but it can’t reflect the influence of the temperature segregation. However, using infrared temperature detector to evaluate the segregation must be taken during paving, which brings much inconvenience. In this paper, measuring the air voids distribution using non-nuclear density gauge to evaluate asphalt pavement segregation was introduced. Result shows that this method can directly reflect the comprehensive results of the two types of segregation in a high efficient and accurate way. Moreover, using the sketch map of segregation area can help to analyze the segregation reason visually.
基金Supported by the National Science Foundation of USA under Grant No. 0630370National Natural Science Foundation of Chinaunder Grant Nos. 90403028 and 11074260
文摘A recently developed B-spline algorithm is extended and utilized to calculate excited states of He atoms in the presence of strong magnetic fields.Binding energies are presented for He in the five excited atomic states 210-+,110-,210-,11(-1)+,and 2 1(1) + with magnetic field strength ranging from 0.0001 to 10 a.u.The obtained energies are compared with available theoretical data,and found to be in good agreement.We investigate influence of magnetic fields on atomic structures of multielectron atoms,and illustrate that how electron probability density distributions change with increasing magnetic field strength.The current approach is directly applicable to simulations of discrete spectra for He atoms in the atmospheres of magnetized white dwarf stars.
