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采用密度泛函理论的局域密度近似(Local Density Approximation,LDA)和广义梯度近似(Generalized Gradient Approximation,GGA)方法,对金红石型RuO2和IrO2的结构进行了计算,获得了体模量、晶胞体积和键长等数据,分析了它们与实验数据的不同原因。结果表明:采用GGA和LDA获得的数据与状态方程式拟合很好,采用LDA计算的稳定状态下的系统形成能E0(绝对值)高于GGA计算的结果,而对超胞体积V0,则是LDA的计算结果小于GGA。两种方法计算出来的体积弹性模量相差将近50 GPa。采用LDA获得的体积弹性模量、晶胞体积、晶体参数和键长均优于GGA计算的结果。引入热膨胀系数对RuO2和IrO2晶胞体积的LDA的计算结果进行修正,可以得到与实验值非常接近的结果。
The structures of rutile RuO2 and IrO2 were calculated by the method of Local Density Approximation (LDA) and Generalized Gradient Approximation (GGA). Density functional theory Volume and bond length and other data, analysis of their different reasons with the experimental data. The results show that the data obtained by GGA and LDA fit well with the state equation, and the system formation energy E0 (absolute value) at steady state calculated by LDA is higher than that by GGA calculation. For the supercell volume V0, LDA calculation results less than GGA. The difference in bulk modulus between the two methods is nearly 50 GPa. The volume elastic modulus, cell volume, crystal parameters and bond length obtained by LDA are all better than those calculated by GGA. With the introduction of thermal expansion coefficient, the calculation results of LDA of unit cell volume of RuO2 and IrO2 are corrected, and the result that is very close to the experimental value can be obtained.