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Accurate Excitation Energies of Point Defects from Fast Particle–Particle Random Phase Approximation Calculations

MetadataDetails
Publication Date2024-03-04
JournalThe Journal of Physical Chemistry Letters
AuthorsJiachen Li, Yu Jin, Jincheng Yu, Weitao Yang, Tianyu Zhu
InstitutionsUniversity of Chicago, Yale University
Citations10

We present an efficient particle-particle random phase approximation (ppRPA) approach that predicts accurate excitation energies of point defects, including the nitrogen-vacancy (NV<sup>-</sup>) and silicon-vacancy (SiV<sup>0</sup>) centers in diamond and the divacancy center (VV<sup>0</sup>) in 4H silicon carbide, with errors of ±0.2 eV compared with experimental values. Starting from the (<i>N</i> + 2)-electron ground state calculated with density functional theory (DFT), the ppRPA excitation energies of the <i>N</i>-electron system are calculated as the differences between the two-electron removal energies of the (<i>N</i> + 2)-electron system. We demonstrate that the ppRPA excitation energies converge rapidly with a few hundred canonical active-space orbitals. We also show that active-space ppRPA has weak DFT starting-point dependence and is significantly cheaper than the corresponding ground-state DFT calculation. This work establishes ppRPA as an accurate and low-cost tool for investigating excited-state properties of point defects and opens up new opportunities for applications of ppRPA to periodic bulk materials.

  1. 1989 - Density-Functional Theory of Atoms and Molecules