以第一性原理计算软件Material Studio的CASTEP模块,对Sr_2Fe Nb O_6(SFN)的结构、性能进行优化模拟,并与实验真实值对比,研究适合于SFN材料体系的交换关联泛函及相关参数的合理设置。具体为:采用不同的交换关联泛函对晶胞进行几何结构...以第一性原理计算软件Material Studio的CASTEP模块,对Sr_2Fe Nb O_6(SFN)的结构、性能进行优化模拟,并与实验真实值对比,研究适合于SFN材料体系的交换关联泛函及相关参数的合理设置。具体为:采用不同的交换关联泛函对晶胞进行几何结构优化,研究不同泛函对晶胞参数计算结果的影响;分别计算电子结构及禁带宽度,并与采用紫外-可见漫反射分析得到的禁带宽度值比较;对体系进行计算收敛测试,判断合适的K点取样、截断能;研究采用Hubbard模型对Fe和Nb赋不同U值对SFN禁带宽度及晶格参数计算结果的影响。结果表明:使用GGA-PBESOL泛函,当K点取样密度为(2×2×2),截断能为400 e V时,已经可以满足基本的计算精度要求;使用GGA+U方法,当UFe=7 e V、UNb=9 e V时,计算出的禁带宽度和晶格常数与实验值符合较好。展开更多
Optical absorption spectra of radical anion C60 after light alkali-dopping havebeen studied by using an extended Hubbard model and two distinct induced spectra havebeen obtained. The result is in agreement with the ex...Optical absorption spectra of radical anion C60 after light alkali-dopping havebeen studied by using an extended Hubbard model and two distinct induced spectra havebeen obtained. The result is in agreement with the experimental one. The spectra havebeen assinged theoretically and the reason for the induced spectra generation has beendiscussed.展开更多
文摘以第一性原理计算软件Material Studio的CASTEP模块,对Sr_2Fe Nb O_6(SFN)的结构、性能进行优化模拟,并与实验真实值对比,研究适合于SFN材料体系的交换关联泛函及相关参数的合理设置。具体为:采用不同的交换关联泛函对晶胞进行几何结构优化,研究不同泛函对晶胞参数计算结果的影响;分别计算电子结构及禁带宽度,并与采用紫外-可见漫反射分析得到的禁带宽度值比较;对体系进行计算收敛测试,判断合适的K点取样、截断能;研究采用Hubbard模型对Fe和Nb赋不同U值对SFN禁带宽度及晶格参数计算结果的影响。结果表明:使用GGA-PBESOL泛函,当K点取样密度为(2×2×2),截断能为400 e V时,已经可以满足基本的计算精度要求;使用GGA+U方法,当UFe=7 e V、UNb=9 e V时,计算出的禁带宽度和晶格常数与实验值符合较好。
文摘Optical absorption spectra of radical anion C60 after light alkali-dopping havebeen studied by using an extended Hubbard model and two distinct induced spectra havebeen obtained. The result is in agreement with the experimental one. The spectra havebeen assinged theoretically and the reason for the induced spectra generation has beendiscussed.
