Verma Shreya, Mitra Abhishek, Jin Yu, Haldar Soumi, Vorwerk Christian, Hermes Matthew R, Galli Giulia, Gagliardi Laura
Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States.
Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
J Phys Chem Lett. 2023 Aug 31;14(34):7703-7710. doi: 10.1021/acs.jpclett.3c01875. Epub 2023 Aug 22.
The optical spectra of neutral oxygen vacancies (F centers) in the bulk MgO lattice are investigated using density matrix embedding theory. The impurity Hamiltonian is solved with the complete active space self-consistent field and second-order -electron valence state perturbation theory (NEVPT2-DMET) multireference methods. To estimate defect-localized vertical excitation energies at the nonembedding and thermodynamic limits, a double extrapolation scheme is employed. The extrapolated NEVPT2-DMET vertical excitation energy value of 5.24 eV agrees well with the experimental absorption maxima at 5.03 eV, whereas the excitation energy value of 2.89 eV at the relaxed triplet defect-localized state geometry overestimates the experimental emission at 2.4 eV by only nearly 0.5 eV, indicating the involvement of the triplet-singlet decay pathway.
利用密度矩阵嵌入理论研究了块状MgO晶格中中性氧空位（F中心）的光谱。杂质哈密顿量采用完全活性空间自洽场和二阶电子价态微扰理论（NEVPT2-DMET）多参考方法求解。为了估计非嵌入和热力学极限下缺陷局域垂直激发能，采用了双外推方案。外推得到的NEVPT2-DMET垂直激发能值5.24 eV与实验吸收最大值5.03 eV吻合良好，而在弛豫三重态缺陷局域态几何结构下2.89 eV的激发能值仅比2.4 eV的实验发射值高估了近0.5 eV，表明存在三重态-单重态衰变途径。
