摘要
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 optimized bulk modulus, supercell volume and bond length were investigated by a plane-wave pseudopotential density functional theory （DFT） method. In order to compare results of calculations and experiments, the Local Density Approximation （LDA） and the Generalized Gradient Approximation （GGA） methods were used. The results show the data calculated by GGA and LDA are fitted well with those of the equation of state. The calculated energy from LDA is larger than that of GGA, while the supercell volume from LDA is smaller than that of GGA. Further, we found that there＇s a difference of nearly 50 GPa for the calculated results between LDA and GGA. The bulk modulus, supercell volume, lattice parameter, and bond length calculated from LDA are more accurate than those of GGA. When the coefficient of thermal expansion is introduced to optimize the LDA method of supercell volume calculation, the result will be in good agreement with the experiment.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2014年第4期951-954,共4页
Rare Metal Materials and Engineering
基金
国家自然科学基金(11104031
50971043
51171046)
福建省教育厅项目(2009J01239)
