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What's the gap? A possible strategy for advancing theory, and an appeal for experimental structure data to drive that advance

机译：什么是差距？ 推进理论的可能策略，以及对实验结构数据的吸引力推动这一推进

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摘要

There is substantial demand for theoretical/computational tools that can produce correct predictions of the geometric structure and band gap to accelerate the design and screening of new materials with desirable electronic properties. DFT-based methods exist that reliably predict electronic structure given the correct geometry. Similarly, when good spectroscopic data are available, these same methods may, in principle, be used as input to the inverse problem of generating a good structural model. The same is generally true for gas-phase systems, for which the choice of method is different, but factors that guide its selection are known. Despite these successes, there are shortcomings associated with DFT for the prediction of materials' electronic structure. The present paper offers a perspective on these shortcomings. Fundamentally, the shortcomings associated with DFT stem from a lack of knowledge of the exact functional form of the exchange-correlation functional. Inaccuracies therefore arise from using an approximate functional. These inaccuracies can be reduced by judicious selection of the approximate functional. Other apparent shortcomings present due to misuse or improper application of the method. One of the most significant difficulties is the lack of a robust method for predicting electronic and geometric structure when only qualitative (connectivity) information is available about the system/material. Herein, some actual shortcomings of DFT are distinguished from merely common improper applications of the method. The role of the exchange functional in the predicted relationship between geometric structure and band gap is then explored, using fullerene, 2D polymorphs of elemental phosphorus and polyacetylene as case studies. The results suggest a potentially fruitful avenue of investigation by which some of the true shortcomings might be overcome, and serve as the basis for an appeal for high-accuracy experimental structure data to drive advances in theory.
机译：对理论/计算工具的需求很大，可以产生对几何结构和带隙的正确预测，以加速具有所需的电子特性的新材料的设计和筛选。存在基于DFT的方法，可靠地预测给出了正确的几何形状的电子结构。类似地，当可用良好的光谱数据时，这些相同的方法原则上可以用作产生良好结构模型的逆问题的输入。对于气相系统而言，该方法通常是真实的，其中方法的选择是不同的，而是指导其选择的因素是已知的。尽管取得了这些成功，但有与DFT相关的缺点，用于预测材料的电子结构。本文提供了对这些缺点的看法。从根本上说，与DFT源的缺点源于缺乏对交换相关功能的确切功能形式的知识。因此，由于使用近似功能而产生不准确性。可以通过明智地选择近似功能来减少这些不准确性。由于滥用或不当应用的方法而存在的其他明显的缺点。最重要的困难之一是缺乏用于预测电子和几何结构的鲁棒方法，当仅在系统/材料上获得定性（连接）信息时。在此，DFT的一些实际缺点与该方法的常见不当应用不同。然后探讨了交换功能在几何结构和带隙之间的预测关系中的作用，使用富勒烯，二维元素磷和聚乙炔的富烯磷和聚乙炔作为案例研究。结果表明，可能会克服一些真正的缺点，并作为高精度实验结构数据的吸引力推动理论步的进步的依据。

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  • 来源
    《RSC Advances》 |2020年第60期|共10页
  • 作者

    Sohlberg Karl; Foster Michael E.;

  • 作者单位

    Drexel Univ Dept Chem Philadelphia PA 19104 USA;

    Drexel Univ Dept Chem Philadelphia PA 19104 USA;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
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