立方结构CaTiO_3晶体物理性质模拟

Study on the Physical Properties of the Perfect Cubic CaTiO_3 Crystal by Computer Simulation

本文运用GULP软件模拟计算了理想立方结构CaTiO3的力学、热学和声子性质。利用正交相结构CaTiO3的晶格结构数据(晶格常数和原子坐标)和晶体性质(弹性常数和高频介电常数)通过GULP的弛豫拟合技术得到理想立方结构CaTiO3的势参数。用该组势参数计算得到的结果和实验结果相吻合。在此基础上计算了理想立方结构CaTiO3的体弹模量、压缩率、杨氏模量、泊松率、弹性常数和高频介电常数。计算并详细分析了理想立方结构CaTiO3沿着高对称方向(X→R;R→M;M→G;G→R)的声子色散曲线和声子态密度。还计算了温度范围为0～1000 K的热容和熵。

The mechanical,thermal and Phonon properties of perfect cubic CaTiO3 have been studied by GULP.The potential parameters used for cubic CaTiO3 have been obtained by the relaxed fitting strategy using the crystallographic data（unit cell lattice parameters and atomic coordinates） and the crystal properties（elastic constants,high frequency dielectric constant） of the orthorhombic perovskite structure of CaTiO3.The calculated results are in good agreement with the experimental results.It is indicated that the potential parameters chosen were valid.The calculated physical properties include bulk modulus,compressibility,Young Modulus,Poisson Ratios,elastic constants,high frequency dielectric constant.The phonon dispersion curves（X→R;R→M;M→G;G→R） and phonon density of states of cubic CaTiO3 were calculated.The heat capacity and entropy are investigated in the 0-1000 K range.