Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, United Kingdom.
J Chem Phys. 2019 Jan 28;150(4):044702. doi: 10.1063/1.5078682.
Using an advanced computational methodology implemented in CP2K, a non-local PBE0-TC-LRC density functional and the recently implemented linear response formulation of the Time-dependent Density Functional Theory equations, we test the interpretation of the optical absorption and photoluminescence signatures attributed by previous experimental and theoretical studies to O-vacancies in two widely used oxides-cubic MgO and monoclinic (m)-HfO. The results obtained in large periodic cells including up to 1000 atoms emphasize the importance of accurate predictions of defect-induced lattice distortions. They confirm that optical transitions of O-vacancies in 0, +1, and +2 charge states in MgO all have energies close to 5 eV. We test the models of photoluminescence of O-vacancies proposed in the literature. The photoluminescence of V centers in m-HfO is predicted to peak at 3.7 eV and originate from radiative tunneling transition between a V center and a self-trapped hole created by the 5.2 eV excitation.
使用在 CP2K 中实现的先进计算方法、非局域 PBE0-TC-LRC 密度泛函和最近实现的含时密度泛函理论方程的线性响应公式，我们检验了先前实验和理论研究归因于两种广泛使用的氧化物——立方 MgO 和单斜 (m)-HfO 中的 O 空位的光学吸收和光致发光特征的解释。在包括多达 1000 个原子的大周期性单元中获得的结果强调了准确预测缺陷诱导的晶格畸变的重要性。它们证实，MgO 中 O 空位的 0、+1 和 +2 电荷状态的光学跃迁的能量都接近 5 eV。我们检验了文献中提出的 O 空位光致发光模型。预测 m-HfO 中的 V 中心的光致发光在 3.7 eV 处出现峰，并源于由 5.2 eV 激发产生的 V 中心和自陷空穴之间的辐射隧穿跃迁。
