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<p>Semilocal density functionals such as the Perdew-Burke-Ernzerhof (PBE) functional substantially underestimate experimental band gaps. Hybrid functionals address this band gap problem by admixing a fraction of Fock exchange to semilocal exchange. The optimal mixing parameter depends on the specific material and can be identified as the inverse dielectric constant (dielectric-dependent hybrid functional, DDH). Here, we show that dielectric constants obtained using the r<sup>2</sup>SCAN meta-GGA functional are significantly more accurate than dielectric constants obtained using the semilocal PBE functional. We propose the DD-r<sup>2</sup>SCANH functional, a dielectric-dependent hybrid functional based on r<sup>2</sup>SCAN. DD-r<sup>2</sup>SCANH can outperform the standard PBE-based DDH in terms of band gaps and other electronic structure properties. Particularly marked improvements are obtained for narrow-gap semiconductors such as Ge and InAs, where PBE wrongly predicts a metallic phase, but r<sup>2</sup>SCAN opens a band gap.</p>

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Dielectric-dependent hybrid functional based on meta-GGA

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月4日

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  • Stefan Riemelmoser,
  • Xun Xu,
  • Alfredo Pasquarello

摘要

Semilocal density functionals such as the Perdew-Burke-Ernzerhof (PBE) functional substantially underestimate experimental band gaps. Hybrid functionals address this band gap problem by admixing a fraction of Fock exchange to semilocal exchange. The optimal mixing parameter depends on the specific material and can be identified as the inverse dielectric constant (dielectric-dependent hybrid functional, DDH). Here, we show that dielectric constants obtained using the r2SCAN meta-GGA functional are significantly more accurate than dielectric constants obtained using the semilocal PBE functional. We propose the DD-r2SCANH functional, a dielectric-dependent hybrid functional based on r2SCAN. DD-r2SCANH can outperform the standard PBE-based DDH in terms of band gaps and other electronic structure properties. Particularly marked improvements are obtained for narrow-gap semiconductors such as Ge and InAs, where PBE wrongly predicts a metallic phase, but r2SCAN opens a band gap.