The Infrared spectrum of very large (periodic) systems: global versus fragment strategies—the case of three defects in diamond

Pascale, Fabien; Salustro, Simone; Ferrari, Anna Maria; Rérat, Michel; D’Arco, Philippe; Dovesi, Roberto

doi:10.1007/s00214-018-2380-3

Cited by 12 publications

(7 citation statements)

References 26 publications

(30 reference statements)

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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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“…Based on the analysis of ideal dravite properties, it can be assumed that the OH stretching frequencies are within ∼ 1 cm −1 from those obtained using the full dynamical matrix. This approach is similar to the partial Hessian techniques which are commonly used to analyze the vibrational properties and contribution to zero point energy of selected parts of extended systems (e.g., Li and Jensen, 2002;Svelle et al, 2008;Ghysels et al, 2010;De Moor et al, 2011;Tao et al, 2018;Pascale et al, 2018;Kraka et al, 2020). Their accuracy has been demonstrated for highly localized vibrations, such as OH stretching modes (e.g., Li and Jensen, 2002;Ghysels et al, 2010).…”

Section: Influence Of Cationic Ordering and X Site Vacancies On Oh Gr...mentioning

confidence: 99%

Theoretical OH stretching vibrations in dravite

2022

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Abstract. Density functional theory is used to investigate the vibrational stretching properties of OH groups in ideal and chemically disordered dravite models. Different schemes of cationic occupancy are considered, including the occurrence of vacancies at the X site and Mg–Al inversion between the Y and Z sites. The harmonic coupling between different OH groups is found to be smaller than 1 cm−1, indicating that the OH stretching dynamic in dravite can be described by considering a collection of nearly independent single OH oscillators. Their harmonic stretching frequency is linearly correlated with the corresponding OH bond length and most of the bands observed in the experimental vibrational spectra can be interpreted as consequences of the cationic occupancy of the sites coordinated to the OH group. The V(OH) and W(OH) stretching frequencies are affected by the Mg–Al inversion and by the presence of vacancies at the X site. In this last case, the frequencies depend on the isolated or more concentrated character of the X vacancy distribution along the c axis. Based on theoretical stretching frequencies, new interpretations are proposed for some of the bands experimentally observed in synthetic samples of dravite and magnesio-foitite.

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“…This strategy, based on the hypothesis of the local character of these isolated modes is at hand with a simple keyword, FRAG-MENT, and is quite effective. 130 It has been applied recently to the investigation of a set of defects in diamond [131][132][133] .…”

Section: The Fragment Strategymentioning

confidence: 99%

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

Dovesi

Pascale

Civalleri

et al. 2020

The Journal of Chemical Physics

Self Cite

163

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 Infrared spectrum of very large (periodic) systems: global versus fragment strategies—the case of three defects in diamond

Abstract: The Infrared spectrum of very large (periodic) systems. Global vs. fragment strategies.

Cited by 12 publications

References 26 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

Theoretical OH stretching vibrations in dravite

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

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