The VN2 negatively charged defect in diamond. A quantum mechanical investigation of the EPR response

Palma, Giulio Di; Gentile, Francesco Silvio; Platonenko, Alexander; Ferrari, Anna Maria; Dovesi, Roberto

doi:10.1016/j.carbon.2019.12.031

Cited by 17 publications

(14 citation statements)

References 44 publications

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“…Second, we used the ab initio periodic code CRYSTAL17, on grounds of computational cost, for hybrid density-functional-theory-Hartree-Fock calculations (B3LYP, HSE06) [54,55]. A number of doped-diamond supercell calculations using the CRYSTAL program have been reported previously [42,43,[56][57][58][59][60][61][62][63][64]. This code uses localised Gaussian basis sets to evaluate energies and associated electronic properties [65][66][67].…”

Section: Theoretical/computational Methodsmentioning

confidence: 99%

Hunting the elusive shallow n-type donor – An ab initio study of Li and N co-doped diamond

Conejeros

Othman

Croot

et al. 2021

Carbon

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We report calculated energetics (at the GGA, and at the B3LYP, HSE06 hybrid density functional levels of theory) and electronic properties (B3LYP, HSE06) of Li and N co-doped diamond containing LiNx clusters (x = 1-4). Defect energies and structural properties at the GGA and hybrid (B3LYP, HSE06) levels of theory are very similar. Our results for isolated Li and N dopants agree with previous work in that they are not suitable candidates for shallow n-type donors. Here, we investigate the effects of addition of N atoms as a co-dopant with Li, which vary with the Li:N ratio and whether Li is interstitial or substitutional.Reaction energies, geometries, bonding and densities of states (DOS) are examined. Nitrogen stabilises substitutional rather than interstitial lithium. Atom-projected DOS show that the chief contributions to the defect states are not from orbitals on the dopant atoms themselves but from states associated with neighbouring carbon atoms. Only the tetrahedral 1:4 cluster, LiCN4, with substitutional Li is likely to behave as a shallow donor. We propose a nonmolecular synthetic route for preparation of the LiCN4-doped material via prior generation of the N4V centre at temperatures at which Li is mobile but LiCN4 clusters are not.

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Section: Theoretical/computational Methodsmentioning

confidence: 99%

Hunting the elusive shallow n-type donor – An ab initio study of Li and N co-doped diamond

Conejeros

Othman

Croot

et al. 2021

Carbon

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“…As shown by a previous paper, the combined use of the B3LYP functional and the triple ζ basis set [20][21][22][23][24][25][26] provides very accurate results for the vibrational spectra, in terms of both wavenumbers and intensities [25,[27][28][29][30][31]. The exchange and Coulomb infinite lattice series can be modified through five parameters, T i , which were set to 8 (T 1 -T 4 ) and 16 (T 5 ).…”

Section: Methodsmentioning

confidence: 99%

Vibrational Analysis of Paraelectric–Ferroelectric Transition of LiNbO3: An Ab-Initio Quantum Mechanical Treatment

et al. 2021

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The phase transitions between paraelectric (PE) and ferroelectric (FE) isomorph phases of LiNbO3 have been investigated quantum mechanically by using a Gaussian-type basis set, the B3LYP hybrid functional and the CRYSTAL17 code. The structural, electronic and vibrational properties of the two phases are analyzed. The vibrational frequencies evaluated at the Γ point indicate that the paraelectric phase is unstable, with a complex saddle point with four negative eigenvalues. The energy scan of the A2u mode at −215 cm−1 (i215) shows a dumbbell potential with two symmetric minima. The isotopic substitution, performed on the Li and Nb atoms, allows interpretation of the nontrivial mechanism of the phase transition. The ferroelectric phase is more stable than the paraelectric one by 0.32 eV.

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“…When the square of the wavefunction magnitude is partitioned according to the Mulliken scheme, the µ values of table IX are obtained. Table X compares the calculated 176,180 and experimental A iso and B tensor values for two defects, namely the C (substitutional nitrogen) and the VN − 2 center. In the first case there is un unpaired electron on one of the first neighbors of N, hence a doublet state.…”

Section: The Epr Parametersmentioning

confidence: 99%

The CRYSTAL code, 1976–2020 and beyond, a long story

Dovesi

Pascale

Civalleri

et al. 2020

The Journal of Chemical Physics

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160

121

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CRYSTAL is a periodic ab initio code that uses a Gaussian-type basis set to express crystalline orbitals (i.e. Bloch functions). The use of atom-centred basis functions allows treating 3D (crystals), 2D (slabs), 1D (polymers) as well as 0D (molecules) systems on the same grounds. In turn, all-electron calculations are inherently permitted along with pseudopotential strategies. A variety of density functionals is implemented, including global and range-separated hybrids of various nature and, as an extreme case, Hartree-Fock (HF). The cost for HF or hybrids is only about 3-5 times larger than when using the local density approximation (LDA) or the generalized gradient approximation (GGA). Symmetry is fully exploited at all steps of the calculation. Many tools are available to modify the structure as given in input and simplify the construction of complicated objects, such as slabs, nanotubes, molecules, clusters. Many tensorial properties can be evaluated by using a single input keyword: elastic, piezoelectric, photoelastic, dielectric, as well as first and second hyperpolarizabilies, etc. The calculation of infrared and Raman spectra is available, and the intensities are computed analytically. Automated tools are available for the generation of the relevant configurations of solid solutions and/or disordered systems. Three versions of the code exist, serial, parallel and massive-parallel. In the second one the most relevant matrices are duplicated on each core, whereas in the third one the Fock matrix is distributed for diagonalization. All the relevant vectors are dynamically allocated and deallocated after use, making the code very agile. CRYSTAL can be used efficiently on high performance computing machines up to thousands of cores.

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The VN2 negatively charged defect in diamond. A quantum mechanical investigation of the EPR response

Cited by 17 publications

References 44 publications

Hunting the elusive shallow n-type donor – An ab initio study of Li and N co-doped diamond

Hunting the elusive shallow n-type donor – An ab initio study of Li and N co-doped diamond

Vibrational Analysis of Paraelectric–Ferroelectric Transition of LiNbO3: An Ab-Initio Quantum Mechanical Treatment

The CRYSTAL code, 1976–2020 and beyond, a long story

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