High-Throughput Search for Triplet Point Defects with Narrow Emission Lines in 2D Materials

Ali, Sajid; Nilsson, Fredrik Andreas; Manti, Simone; Bertoldo, Fabian; Mortensen, Jens Jørgen; Thygesen, Kristian Sommer

doi:10.1021/acsnano.3c04774

Cited by 4 publications

(4 citation statements)

References 53 publications

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“…More recently, the approach has been applied in density functional calculations of a large set of Rydberg excited states of molecules using GGA, meta-GGA as well as self-interaction-corrected functionals . DO has also been used in the calculations of excited states of solid-state systems with quantum point defects. − …”

Section: Introductionmentioning

confidence: 99%

Orbital-Optimized Versus Time-Dependent Density Functional Calculations of Intramolecular Charge Transfer Excited States

Selenius,

Sigurdarson,

Schmerwitz

et al. 2024

J. Chem. Theory Comput.

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The performance of time-independent, orbital-optimized calculations of excited states is assessed with respect to charge transfer excitations in organic molecules in comparison to the linear-response time-dependent density functional theory (TD-DFT) approach. A direct optimization method to converge on saddle points of the electronic energy surface is used to carry out calculations with the local density approximation (LDA) and the generalized gradient approximation (GGA) functionals PBE and BLYP for a set of 27 excitations in 15 molecules. The time-independent approach is fully variational and provides a relaxed excited state electron density from which the extent of charge transfer is quantified. The TD-DFT calculations are generally found to provide larger charge transfer distances compared to the orbital-optimized calculations, even when including orbital relaxation effects with the Z-vector method. While the error on the excitation energy relative to theoretical best estimates is found to increase with the extent of charge transfer up to ca. −2 eV for TD-DFT, no correlation is observed for the orbital-optimized approach. The orbital-optimized calculations with the LDA and the GGA functionals provide a mean absolute error of ∼0.7 eV, outperforming TD-DFT with both local and global hybrid functionals for excitations with a long-range charge transfer character. Orbital-optimized calculations with the global hybrid functional B3LYP and the range-separated hybrid functional CAM-B3LYP on a selection of states with short-and long-range charge transfer indicate that inclusion of exact exchange has a small effect on the charge transfer distance, while it significantly improves the excitation energy, with the best-performing functional CAM-B3LYP providing an absolute error typically around 0.15 eV.

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Section: Introductionmentioning

confidence: 99%

Orbital-Optimized Versus Time-Dependent Density Functional Calculations of Intramolecular Charge Transfer Excited States

Selenius,

Sigurdarson,

Schmerwitz

et al. 2024

J. Chem. Theory Comput.

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“…44−46 However, some databases contain both TMD-and hBN-based quantum emitters and use the same functional for all materials. 42,44,46 This results in an overall comprehensive database but not all functionals might be equally good for all materials. In contrast, there are also exclusive hBN defects databases, 44,46 however, there do not contain the complete optical fingerprint of many hBN defects.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, numerous databases have vastly been developed to collect properties of a large number of defects in 2D materials. These include machine-learning-based databases − and DFT-based databases. − The former can handle a large number of data sets but the prediction of promising candidates still requires a DFT calculation for confirmation. In general, a machine-learned database is sufficient for predicting promising new defects that one could fabricate but for defect identification one needs the most accurate data.…”

Section: Introductionmentioning

confidence: 99%

“…In general, a machine-learned database is sufficient for predicting promising new defects that one could fabricate but for defect identification one needs the most accurate data. This can be offered by DFT calculations: the available databases contain structural, electronic, and energetic properties, − Raman spectra, and photophysical properties of point defects. − However, some databases contain both TMD- and hBN-based quantum emitters and use the same functional for all materials. ,, This results in an overall comprehensive database but not all functionals might be equally good for all materials. In contrast, there are also exclusive hBN defects databases, , however, there do not contain the complete optical fingerprint of many hBN defects.…”

Section: Introductionmentioning

confidence: 99%

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The hBN Defects Database: A Theoretical Compilation of Color Centers in Hexagonal Boron Nitride

Cholsuk,

Zand,

Çakan

et al. 2024

J. Phys. Chem. C

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Color centers in hexagonal boron nitride (hBN) have become an intensively researched system due to their potential applications in quantum technologies. There has been a large variety of defects being fabricated, yet, for many of them, the atomic origin remains unclear. The direct imaging of the defect is technically very challenging, in particular since, in a diffractionlimited spot, there are many defects and then one has to identify the one that is optically active. Another approach is to compare the photophysical properties with theoretical simulations and identify which defect has a matching signature. It has been shown that a single property for this is insufficient and causes misassignments.Here, we publish a density functional theory-based searchable online database covering the electronic structure of hBN defects (257 triplet and 211 singlet configurations), as well as their photophysical fingerprint (excited state lifetime, quantum efficiency, transition dipole moment and orientation, polarization visibility, and many more). All data is open-source and publicly accessible at https://h-bn.info and can be downloaded. It is possible to enter the experimentally observed defect signature and the database will output possible candidates which can be narrowed down by entering as many observed properties as possible. The database will be continuously updated with more defects and new photophysical properties (which can also be specifically requested by any users).The database therefore allows one to reliably identify defects but also investigate which defects might be promising for magnetic field sensing or quantum memory applications.

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Hexagonal Boron Nitride Quantum Simulator: Prelude to Spin and Photonic Qubits

Cobarrubia,

Schottle,

Suliman

et al. 2024

ACS Nano

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The quest for qubit operation at room temperature is accelerating the field of quantum information science and technology. Solid state quantum defects with spin-optical properties are promising spin- and photonic qubit candidates for room temperature operations. In this regard, a single boron vacancy within hexagonal boron nitride (h-BN) lattice such as V B – defect has coherent quantum interfaces for spin and photonic qubits owing to the large band gap of h-BN (6 eV) that can shield a computational subspace from environmental noise. However, for a V B – defect in h-BN to be a potential quantum simulator, the design and characterization of the Hamiltonian involving mutual interactions of the defect and other degrees of freedom are needed to fully understand the effect of defects on the computational subspace. Here, we studied the key coupling tensors such as zero-field splitting, Zeeman effect, and hyperfine splitting in order to build the Hamiltonian of the V B – defect. These eigenstates are spin triplet states that form a computational subspace. To study the phonon-assisted single photon emission in the V B – defect, the Hamiltonian is characterized by electron–phonon interaction with Jahn–Teller distortions. A theoretical demonstration of how the V B – Hamiltonian is utilized to relate these quantum properties to spin- and photonic-quantum information processing. For selecting promising host 2D materials for spin and photonic qubits, we present a data-mining perspective based on the proposed Hamiltonian engineering of the V B – defect in which h-BN is one of four materials chosen to be room temperature qubit candidates.

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High-Throughput Search for Triplet Point Defects with Narrow Emission Lines in 2D Materials

Cited by 4 publications

References 53 publications

Orbital-Optimized Versus Time-Dependent Density Functional Calculations of Intramolecular Charge Transfer Excited States

Orbital-Optimized Versus Time-Dependent Density Functional Calculations of Intramolecular Charge Transfer Excited States

The hBN Defects Database: A Theoretical Compilation of Color Centers in Hexagonal Boron Nitride

Hexagonal Boron Nitride Quantum Simulator: Prelude to Spin and Photonic Qubits

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