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Perspectives on van der Waals Density Functionals: The Case of TiS2
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2020-11-15 , DOI: 10.1021/acs.jpca.0c05973
Jaron T. Krogel 1, 2 , Simuck F. Yuk 1 , Paul R. C. Kent 2 , Valentino R. Cooper 1
Affiliation  

The van der Waals interaction is of foundational importance for a wide variety of physical systems. In particular, van der Waals forces lie at the heart of potential device technologies that may be realized from the functional organization of layered two-dimensional (2D) nanomaterials. For intermediate to large-scale applications modeling, van der Waals density functionals have become the de facto choice for first-principles calculations. In particular, the vdW-DF family of functionals have provided a systematic approach to this theoretically challenging problem. While much progress has been made, there remains room for improvement in the microscopic description of vdW forces from these density functionals. In this work, we compute benchmark results for the binding energy and the electronic density response to binding in TiS2 via accurate diffusion quantum Monte Carlo calculations. We compare these benchmark data to results obtained from local, semilocal, and van der Waals functionals. In particular, we gauge the quality of the original vdW-DF/vdW-DF2 functionals, as well as updated variants such as vdW-DF-C09, vdW-DF-optB88, vdW-DF-optB86b, and vdW-DF2-B86R. We find a close relationship between the accuracy of predicted interlayer separation distances and binding energies for TiS2, with the vdW-DF-optB88 functional performing very well in terms of both quantities. In general, the more recently developed functionals are systematic improvements over older ones. However, when considering the response of the electron density to binding, we find that local-density approximation (LDA) and PBEsol generally outperform the vdW-DF functionals in describing the interlayer charge accumulation with vdW-DF-C09 variants performing the best overall.

中文翻译:

Van der Waals密度泛函的观点:TiS 2的情况

范德华相互作用对于各种物理系统都具有根本的重要性。特别地,范德华力是潜在的设备技术的核心,可以从层状二维(2D)纳米材料的功能组织中实现。对于中大型应用程序建模,范德华密度函数已成为事实第一性原理计算的选择。特别是vdW-DF系列功能为解决这一理论上具有挑战性的问题提供了系统的方法。尽管已经取得了很大的进步,但是在这些密度泛函的vdW力的微观描述中仍有改进的空间。在这项工作中,我们计算TiS 2中结合能和电子密度对结合的响应的基准结果通过精确的扩散量子蒙特卡罗计算。我们将这些基准数据与从局部,半局部和范德华函数获得的结果进行比较。特别是,我们会评估原始vdW-DF / vdW-DF2功能以及更新的变体(例如vdW-DF-C09,vdW-DF-optB88,vdW-DF-optB86b和vdW-DF2-B86R)的质量。我们发现预测的层间分离距离的准确性与TiS 2的结合能之间存在密切关系,其中vdW-DF-optB88功能在两个数量上都表现出色。通常,较新开发的功能是对较旧功能的系统改进。但是,当考虑电子密度对结合的响应时,我们发现在描述整体上表现最佳的vdW-DF-C09变体的层间电荷积累时,局部密度近似(LDA)和PBEsol通常优于vdW-DF的功能。
更新日期:2020-11-25
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