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Clarify the optical nature of the MgO F0-center

Determine the nature of the optical properties of the neutral oxygen vacancy (F0 center) in magnesium oxide (MgO), identifying the electronic transitions and states responsible for its observed absorption and photoluminescence features, which have remained unresolved despite extensive prior experimental and computational studies.

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Background

The neutral oxygen vacancy (F0 center) in MgO introduces a mid-gap localized defect state and additional defect-localized states within the conduction band. Experimentally, MgO with oxygen vacancies exhibits an absorption feature near 5.03 eV and photoluminescence bands around 2.3 eV and 3.2 eV, but the assignment of these features to specific defects and electronic transitions has been debated.

Multiple interpretations exist for the photoluminescence mechanism and the assignment of the observed peaks to F0 and F+ centers. Prior studies using diverse methodologies (e.g., FN-DMC, GW-BSE, EOM-CCSD, TDDFT, DMET, CASPT2) have reached differing conclusions, motivating a clear determination of the transitions and states underlying the optical response of the F0 center.

References

To test our implementation we have studied the optical properties of the $F0$-center (neutral oxygen vacancy) in magnesium oxide, whose nature remains unclear despite the many experimental and computational studies carried out in the past decades.

— A general framework for active space embedding methods: applications in quantum computing (2404.18737 - Battaglia et al., 29 Apr 2024) in Section 4 Results and discussion, first paragraph