Theoretical spectroscopy of the v N N B defect in hexagonal boron nitride

A. Sajid, Jeffrey R. Reimers, Rika Kobayashi, Michael J. Ford

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The VNNB defect in hexagonal boron nitride (h-BN), comprising a nitrogen vacancy adjacent to a nitrogen-for-boron substitution, is modelled in regard to its possible usefulness in a nanophotonics device. The modelling is done on both a simple model compound and on a 2D periodic representation of the defect, considering its magnetic and spectroscopic properties. The electronic distribution in most excited states of VNNB is found to be very open-shell in nature, and to deal with this two new computational methods are developed: one allows standard density-functional theory (DFT) calculations to be employed to evaluate state energies for doublet states with three unpaired electrons, the other introduces techniques needed to apply the vasp computational package to these and many other problems involving excited states. Also of general use, results from DFT calculations are then calibrated against those from the ab initio methods MRCI, CASPT2, CCSD, EOM-CCSD, and CCSD(T), seeking robust computational schemes. This complements previous work to reveal quite different properties for systems with odd and even numbers of electrons. These innovations allow 45 electronic states of the defect in its neutral, +1 and -1 charged forms to be considered. The charged forms of the defect are predicted to display properties of potential interest to nanophotonics.

Original languageEnglish
Article number144104
Number of pages15
JournalPhysical Review B
Issue number14
Publication statusPublished - 12 Oct 2020
Externally publishedYes

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