Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland.
Institute of Theoretical Physics and Astrophysics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, ul. Wita Stwosza 57, 80-308 Gdańsk, Poland.
J Phys Chem A. 2023 Jun 1;127(21):4583-4595. doi: 10.1021/acs.jpca.2c07979. Epub 2023 May 17.
We propose a universal approach to model intervalence charge transfer (IVCT) and metal-to-metal charge transfer (MMCT) transitions between ions in solids. The approach relies on already well-known and reliable ab initio RASSCF/CASPT2/RASSI-SO calculations for a series of emission center coordination geometries (restricted active space self-consistent field, complete active space second-order perturbation theory, and restricted active space state interaction with spin-orbit coupling). Embedding with ab initio model potentials (AIMPs) is used to represent the crystal lattice. We propose a way to construct the geometries via interpolation of the coordinates obtained using solid-state density functional theory (DFT) calculations for the structures where the activator metal is at specific oxidation (charge) states of interest. The approach thus takes the best of two worlds: the precision of the embedded cluster calculations (including localized excited states) and the geometries from DFT, where the effects of ionic radii mismatch (and eventual nearby defects) can be modeled explicitly. The method is applied to the Pr activator and Ti, Zr, Hf codopants in cubic LuO, in which the said ions are used to obtain energy storage and thermoluminescence properties. Electron trap charging and discharging mechanisms (not involving a conduction band) are discussed in the context of the IVCT and MMCT role in them. Trap depths and trap quenching pathways are analyzed.
我们提出了一种通用方法来模拟固体中离子之间的范德华电荷转移（IVCT）和金属-金属电荷转移（MMCT）跃迁。该方法依赖于已经众所周知且可靠的从头算 RASSCF/CASPT2/RASSI-SO 计算，用于一系列发射中心配位几何形状（受限活性空间自洽场、完全活性空间二阶微扰理论和具有自旋轨道耦合的受限活性空间态相互作用）。嵌入的从头算模型势（AIMPs）用于表示晶体晶格。我们提出了一种通过插值由固态密度泛函理论（DFT）计算得到的坐标来构建几何形状的方法，这些坐标用于结构中激活金属处于特定氧化（电荷）态的情况。因此，该方法结合了两种方法的优势：嵌入簇计算的精度（包括局域激发态）和 DFT 的几何形状，其中可以显式地模拟离子半径失配（和最终附近的缺陷）的影响。该方法应用于立方 LuO 中的 Pr 激活剂和 Ti、Zr、Hf 共掺杂剂，其中所述离子用于获得储能和热发光性能。在 IVCT 和 MMCT 作用的背景下，讨论了电子陷阱的充电和放电机制（不涉及导带）。分析了陷阱深度和陷阱猝灭途径。
