论文标题
与CS $ _2 $$ B $$ B'$$ x_6 $ Double Perovskites的几何和电子结构的确切交换的重要性
Importance of exact exchange to the geometric and electronic structures of Cs$_2$$B$$B'$$X_6$ double perovskites
论文作者
论文摘要
我们研究了通过First-principles计算，我们调查了无铅卤化双钙质（HDPS）CS $ _2BB'X_6 $（$ b $ = ag，na; $ b'ub = in，bi; $ x $ = cl，br）。我们发现，Heyd-Scuseria-Ernzerhof（HSE）杂交功能获得的HDP的几何结构和电力结构都比Perdew-Burke-ernzerhof（PBE）功能好得多。重要的是，我们发现DHP的电子结构对它们的几何形状非常敏感，尤其是$ b $ - $ x $债券长度。结果，使用PBE优化的几何形状通过HSE功能计算的电子结构仍可能显着低估带隙，而HSE优化几何形状上的计算可提供更令人满意的结果。 DHP对几何形状的频带间隙的敏感性为通过掺杂和合金化的带结构工程开辟了有希望的路径。因此，这项工作为进一步改善HDP材料提供了有用的指南。
We investigate the lead-free halide double perovskites (HDPs) Cs$ _2BB'X_6$ ($B$=Ag, Na; $B'$=In, Bi; $X$=Cl, Br) via first-principles calculations. We find that both the geometric and electric structures of the HDPs obtained by the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional are much better than those of the Perdew-Burke-Ernzerhof (PBE) functional. Importantly, we find that the electronic structures of DHPs are very sensitive to their geometries, especially the $B$-$X$ bond lengths. As a consequence, the electronic structures calculated by the HSE functional using the PBE optimized geometries may still significantly underestimate the band gaps, whereas the calculations on the HSE optimized geometries provide much more satisfactory results. The sensitivity of the band gaps of the DHPs to their geometries opens a promising path for the band structure engineering via doping and alloying. This work therefore provides an useful guideline for further improvement of HDPs materials.
