Bright oxygen- and vacancy-derived spin-singlet diamond color centers with metastable spin triplets: OV$^{2+}$ and VOV$^{2+}$

Quantum Physics [Submitted on 20 Mar 2026] Bright oxygen- and vacancy-derived spin-singlet diamond color centers with metastable spin triplets: OV^{2+} and VOV^{2+} John Mark P. Martirez The ST1 diamond color center was experimentally demonstrated to involve a substitutional oxygen atom (O_C) and carbon vacancy (V_C), has a spin singlet ground-state, and a metastable electron spin ancilla: a triplet. ST1's structure was left unsolved for more than a decade. With embedded multiconfigurational quantum mechanical theory, we investigate O_C-V_C-derived diamond defects, specifically both 0 and +2-charged coupled O_CV_C, and O_C surrounded by V_Cs along the [110] axis (V_CO_CV_C). We found both O_CV_{C}^{2+} (C_{3v}) and V_CO_CV_{C}^{2+} (C_{2v}) to have a spin-singlet ground state (1^1A_1) and metastable spin triplets. We demonstrate ST1 to be V_CO_CV_{C}^{2+}. The calculated vertical excitation energies of V_CO_CV_{C}^{2+}'s first (1^1B_2) and second (2^1A_1) bright spin-singlet excited states closely match ST1's experimental zero phonon line (2.2-2.3 eV). O_CV_{C}^{2+} (^1E) absorbs much higher (2.8 eV). The two O lone pairs favor V_CO_CV_C over O_CV_C, in a similar manner as the single N lone pair favors formation of N_CV_C centers. Subjects: Quantum Physics (quant-ph); Materials Science (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el) Cite as: arXiv:2603.20073 [quant-ph]   (or arXiv:2603.20073v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.20073 Focus to learn more Submission history From: John Mark Martirez [view email] [v1] Fri, 20 Mar 2026 15:54:54 UTC (1,885 KB) Access Paper: view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 Change to browse by: cond-mat cond-mat.mtrl-sci cond-mat.str-el References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)