压强下TaB_2力学性质的第一性原理研究

First-principles study on mechanical properties of TaB_2 under pressure

采用基于密度泛函理论的第一性原理赝势平面波方法,在广义梯度近似下运用纯理论计算方法得到TaB2的晶格常数、弹性模量、切变模量和泊松比等力学参数,研究了TaB2在不同压强下的弹性常数、体弹模量和态密度.结果表明:随着压强的增加,TaB2的弹性常数和体弹模量随之增加,而相对晶格常数和相对体积则随着压强的增加而减小;在一定压强下,TaB2沿着c轴方向的压缩性要比a轴方向的大.依据Bardeen-Cooper-Schrieffer超导理论,TaB2在其费米能级处的态密度值随着压强的增加而降低,说明它的超导转变温度Tc随着压强的增加而降低.

The elastic constants,structural parameters,electronic structure and superconducting properties of TaB2 under pressure are investigated by using frst-principles plane-wave pseudopotential density functional theory within the generalized gradient approximation（GGA）.It is found that the elastic constants and bulk modulus of TaB2 increase with pressure,while the relative lattice constants and relative volume decrease with pressure.Under high pressure,different layers compression of TaB2 is larger than the same layer compression of TaB2.According to Bardeen-Cooper-Schrieffer（BCS） theory of superconductivity,the values of density of states（DOS） at the Fermi level of TaB2 decrease with pressure,which indicates that their superconducting transition temperatures Tc decrease as pressure increases.