高压下ErNi2B2C弹性性质、电子结构和热力学性质的第一性原理研究

采用密度泛函理论中的赝势平面波方法研究了高压下超导材料 ErNi₂B₂C 的弹性性质、电子结构和热力学性质.分析表明, 弹性常数、体弹模量、剪切模量、杨氏模量和弹性各向异性因子的外压力效应明显. 电子态密度(DOS)的计算结果显示, 在费米能级(E_F)处的 DOS 峰随外界压强的增大显著降低, 由于 ErNi₂B₂C 相对较高的超导温度(T_c)起因于E_F处的 DOS 峰, 因此推测压强增大可能会降低 ErNi₂B₂C 的 T_c.类似的现象在超导材料 MgB₂和 SrAlSi 中已被发现.此外, 基于准谐德拜模型, 对 ErNi₂B₂C 在高温高压下的热力学性质的研究表明, 在一定范围内, 温度和压强将对其热膨胀系数和热容产生明显的影响. 关键词： 高压 弹性性质 电子结构 热力学性质

First-principles study on the elastic,electronic and thermodynamic properties of ErNi2B2C under high pressure

The elastic, electronic and thermodynamic properties of the superconducting ErNi₂B₂C material at high pressure are investigated using the plane-wave pseudopotential density functional theory. The analysis shows the dependences of the elastic constants, bulk modulus, shear modulus, Young's modulus and elastic anisotropy factors on the applied pressure. The calculated electronic density of states (DOS) reveals that the DOS peak at the Fermi level (E_F) will decrease noticeably with pressure. It can be concluded that the pressure may reduce the superconducting temperature (T_c) of ErNi₂B₂C since the relatively high T_c originates from the peak in the DOS. This phenomenon is also found in some other superconductors such as MgB₂ and SrAlSi. Moreover, based on the quasi-harmonic Debye model, the results of the thermodynamic properties indicate that the pressure and temperature have significant influences on the thermal expansion coefficient and heat capacity.
Keywords： high pressure elastic properties electronic structure thermodynamic properties