The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTALO3 program. The lattice parameters, the bulk modulus, the heat capacity, the Gruneieen parameter, and the Debye temper...The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTALO3 program. The lattice parameters, the bulk modulus, the heat capacity, the Gruneieen parameter, and the Debye temperature are obtained. The results are in good agreement with the available experimental and theoretical data. Moreover, the relationship between V/V0 and pressure, the elastic constants under high pressure are successfully obtained. Especially, the elastic constants of diamond under high pressure are firstly obtained theoretically. At the same time, the variations of the thermal expansion α with pressure P and temperature Tare obtained systematically in the ranges of 0-870 GPa and 0-1600 K.展开更多
The electron transport properties of a silicon atomic chain sandwiched between Au(100)leads are investigated by using the density functional theory combined with the non-equilibrium Green's function method.The bre...The electron transport properties of a silicon atomic chain sandwiched between Au(100)leads are investigated by using the density functional theory combined with the non-equilibrium Green's function method.The breaking process of Au-Si4-Au nanoscale junctions is simulated.The conductance and the corresponding cohesion energy as a function of distance dz are obtained.With the increase of distance,the conductance decreases.When dz=18.098 A,there is a minimum value of cohesion energy.The nanoscale structure of junctions is most stable,and the equilibrium conductance is 1.71G_(0)(G_(0)=2e^(2)/h)at this time.The I–V curves of junctions at equilibrium position show linear characteristics.展开更多
Contact geometry and electronic transport properties of a silicon atom sandwiched between Au electrodes in three different anchoring configurations are investigated by using the density functional theory combined with...Contact geometry and electronic transport properties of a silicon atom sandwiched between Au electrodes in three different anchoring configurations are investigated by using the density functional theory combined with the non?equilibrium Green function method.We simulate the nanoscale junction breaking process and calculate the corresponding cohesion energy,obtain the equilibrium conductance and the projected density of states of junctions in an optimal postion.We also calculate the conductance and the current of junctions at the equilibrium position under small bias voltage.It is found that all junctions have large conductance and show a linear I–V relationship,but the current and conductance of a hollow-hollow configuration is always the biggest under the voltage range of-1.2 V~1.2V.The calculated results proved that the coupling morphology of a silicon atom connected with electrodes has an important effect on the electronic transport properties of the nanoscale junction.展开更多
The elastic constants of superconducting MgB2 are calculated using a molecular dynamics method (MD)with shell model. The lattice parameters, five independent elastic constants, equations of state (EOS), Debye temperat...The elastic constants of superconducting MgB2 are calculated using a molecular dynamics method (MD)with shell model. The lattice parameters, five independent elastic constants, equations of state (EOS), Debye temperature, and bulk modulus of MgB2 are obtained. Meanwhile, the dependence of the bulk modulus B, the lattice parameters a and c, and the unit cell volume V on the applied pressure are presented. It is demonstrated that the method introduced here can well reproduce the experimental results with a reasonable accuracy.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No. 10776022
文摘The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTALO3 program. The lattice parameters, the bulk modulus, the heat capacity, the Gruneieen parameter, and the Debye temperature are obtained. The results are in good agreement with the available experimental and theoretical data. Moreover, the relationship between V/V0 and pressure, the elastic constants under high pressure are successfully obtained. Especially, the elastic constants of diamond under high pressure are firstly obtained theoretically. At the same time, the variations of the thermal expansion α with pressure P and temperature Tare obtained systematically in the ranges of 0-870 GPa and 0-1600 K.
基金Support by the National Natural Science Foundation of China under Grant Nos 11174214 and 11204192the Research Project of Education Department in Sichuan Province under Grant No 13ZB0207.
文摘The electron transport properties of a silicon atomic chain sandwiched between Au(100)leads are investigated by using the density functional theory combined with the non-equilibrium Green's function method.The breaking process of Au-Si4-Au nanoscale junctions is simulated.The conductance and the corresponding cohesion energy as a function of distance dz are obtained.With the increase of distance,the conductance decreases.When dz=18.098 A,there is a minimum value of cohesion energy.The nanoscale structure of junctions is most stable,and the equilibrium conductance is 1.71G_(0)(G_(0)=2e^(2)/h)at this time.The I–V curves of junctions at equilibrium position show linear characteristics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174214 and 11204192the Research Project of Education Department in Sichuan Province under Grant No 13ZB0207.
文摘Contact geometry and electronic transport properties of a silicon atom sandwiched between Au electrodes in three different anchoring configurations are investigated by using the density functional theory combined with the non?equilibrium Green function method.We simulate the nanoscale junction breaking process and calculate the corresponding cohesion energy,obtain the equilibrium conductance and the projected density of states of junctions in an optimal postion.We also calculate the conductance and the current of junctions at the equilibrium position under small bias voltage.It is found that all junctions have large conductance and show a linear I–V relationship,but the current and conductance of a hollow-hollow configuration is always the biggest under the voltage range of-1.2 V~1.2V.The calculated results proved that the coupling morphology of a silicon atom connected with electrodes has an important effect on the electronic transport properties of the nanoscale junction.
基金中国科学院资助项目，Scientific Research Foundation for Returned Overseas Chinese Scholars，Ministry of Education of China
文摘The elastic constants of superconducting MgB2 are calculated using a molecular dynamics method (MD)with shell model. The lattice parameters, five independent elastic constants, equations of state (EOS), Debye temperature, and bulk modulus of MgB2 are obtained. Meanwhile, the dependence of the bulk modulus B, the lattice parameters a and c, and the unit cell volume V on the applied pressure are presented. It is demonstrated that the method introduced here can well reproduce the experimental results with a reasonable accuracy.
