SrCoO3的电子结构、弹性及热力学性质的第一性原理计算

First-principles calculation of electronic, elastic, phonon and thermal properties of SrCoO3

采用基于密度泛函理论的第一性原理计算方法研究了SrCoO 3立方相的电子结构、弹性以及晶格振动的声子谱和热力学性质.通过理论计算给出了立方相SrCoO 3的晶格常数、弹性常数以及体弹性模量和剪切模量等参数.结合能带结构和电子态密度的分析,研究了SrCoO 3的铁磁性质,结果表明Co原子中3d电子处于中间自旋态.通过声子色散关系的计算,发现低温下SrCoO 3立方相可能会发生四方结构的相变.为了得到不同温度和压强下SrCoO 3立方相的热力学性质,采用准谐德拜模型进行了计算和拟合,给出了0~12 GPa和0~700 K范围内晶格常数、热膨胀系数和比热容的变化,并比较了两种不同德拜模型的理论计算结果.

The structural,electronic,elastic,phonon and thermal properties of the cubic phase SrCoO 3 were investigated by first-principles calculation based on density functional theory.The ground state quantities such as lattice parameter,bulk and shear modulus,and the elastic constants have been given by theoretical calculations.The results of electronic band structure and densities of states indicated that SrCoO 3 was a ferromagnetic metallic perovskite and possessed an intermediate spin state.The phonon dispersion spectrum results revealed that the cubic phase of SrCoO 3 was dynamically unstable at low temperature.Two Debye models based on quasiharmonic approximation were used to obtain the thermodynamic properties of SrCoO 3 in the range of 0~12 GPa and 0~700 K.