Wavefunction character of the F-center in table salt

Fang, Chun; Groot, de Robert

doi:10.1088/0953-8984/20/7/075219

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…The calculated band gap is therefore generally smaller than experimental value, and the underestimation is more pronounced for wide band gap insulators. For NaCl, DFT calculations predict band gaps from 4.5 eV to 5.0 eV [32][33][34] , much smaller than the experimental value (8.5 eV) 35 . The band-gap problem poses serious uncertainties to the positions of the defect electronic levels and makes the credibility of the calculation questionable.…”

Section: Introductionmentioning

confidence: 60%

Color centers in NaCl by hybrid functionals

et al. 2010

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We present in this work the electronic structure and transition energies ͑both thermodynamic and optical͒ of Cl vacancies in NaCl by hybrid density functionals. The underestimated transition energies by the semilocal functional inherited from the band-gap problem are recovered by the PBE0 hybrid functional through the nonlocal exact exchange, whose amount is adjusted to reproduce the experimental band gap. The hybrid functional also gives a better account of the lattice relaxation for the defect systems arising from the reduced self-interaction. On the other hand, the quantitative agreement with experimental vertical transition energy cannot be achieved with hybrid functionals due to the inaccurate descriptions of the ionization energies of the localized defect and the positions of the band edges.

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Section: Introductionmentioning

confidence: 60%

Color centers in NaCl by hybrid functionals

et al. 2010

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“…In order to demonstrate the feasibility of corresponding open-shell excited-state calculations with MSINDO-CCM-UCIS we selected the most frequently studied system NaCl as an example. There exists a number of previous theoretical studies on this system, comprising embedded-cluster UHF and MP2 (Møller-Plesset perturbation theory of second-order) calculations, 59,60 localized spherical-wave DFT 61 and periodic UHF and HF-DFT hybrid methods. 62 In the former three studies [59][60][61] local s-and p-type orbitals were used to describe the defect electron.…”

Section: Application Of Ucis: F-centers In Naclmentioning

confidence: 99%

“…There exists a number of previous theoretical studies on this system, comprising embedded-cluster UHF and MP2 (Møller-Plesset perturbation theory of second-order) calculations, 59,60 localized spherical-wave DFT 61 and periodic UHF and HF-DFT hybrid methods. 62 In the former three studies [59][60][61] local s-and p-type orbitals were used to describe the defect electron. Their shapes and energies were used to interpret the extension of the defect and the defect levels.…”

Section: Application Of Ucis: F-centers In Naclmentioning

confidence: 99%

Periodic calculations of excited state properties for solids using a semiempirical approach

Gadaczek

Hintze

Bredow

2012

Phys. Chem. Chem. Phys.

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The semiempirical SCF MO method MSINDO (modified symmetrically orthogonalized intermediate neglect of differential overlap) [T. Bredow and K. Jug, Electronic Encyclopedia of Computational Chemistry, 2004] is extended to the calculation of excited state properties through implementation of the configuration interaction singles (CIS) approach. MSINDO allows the calculation of periodic systems via the cyclic cluster model (CCM) [T. Bredow et al., J. Comput. Chem., 2001, 22, 89] which is a direct-space approach and therefore can be in principle combined with all molecular quantum-chemical techniques. The CIS equations are solved for a cluster with periodic boundary conditions using the Davidson-Liu iterative block diagonalization approach. As a proof-of-principle, MSINDO-CCM-CIS is applied for the calculation of optical spectra of ZnO and TiO(2), oxygen-defective rutile, and F-centers in NaCl. The calculated spectra are compared to available experimental and theoretical literature data. After re-adjustment of the empirical parameters the quantitative agreement with experiment is satisfactory. The present approximate approach is one of the first examples of a quantum-chemical methodology for solids where excited states are correctly described as n-electron state functions. After careful benchmark testing it will allow calculation of photophysical and photochemical processes relevant to materials science and catalysis.

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“…The electronic properties of the F center are well studied with a plethora of theoretical methods. − Its reactivity was explored for NaCl and KCl both in experiments − and theoretically using density functional theory (DFT) studies. ,,− It acts as a strong, local reduction site, and readily transfers the defect electron to a wide range of organic molecules. This makes it an interesting candidate for catalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

Mobility of F Centers in Alkali Halides

Häfner

Bredow

2021

J. Phys. Chem. C

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The migration of F centers in alkali halides is important both for characterizing their chemical reactivity and as a benchmark for theoretical methods. In order to provide a solid basis for the assessment of theoretical methods, we reviewed the available experimental literature on the migration of F centers in NaCl, KCl, NaBr, and KBr. The migration of the F center through the bulk, across the (100) surface, and from the surface into the bulk was modeled. The activation enthalpy for the migration of an F center was calculated using dispersion-corrected generalized gradient approximation (GGA) functionals and a self-consistent dielectric-dependent global hybrid method based on plane-wave functions for the bulk and the (100) surface. The geometries of the transition states were characterized, and the position of the defect electron was determined. The influence of the theoretical methodology and the temperature dependence of the lattice parameter on the migration barrier was investigated. For the description of the bulk, thermal corrections were considered to enhance comparability with the experiment. The calculated migration enthalpies of 1.31, 1.46, and 1.32 eV for NaCl, KCl, and KBr, respectively, agree well with experimental measurements. For NaBr, a migration enthalpy of 0.93 eV is predicted. While only a direct hopping process between neighboring anion sites is found for the bulk, there are two possible pathways for some surfaces. The migration barrier on the surface and from the surface into the bulk is predicted to be lower than that in the bulk in all cases.

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Wavefunction character of the F-center in table salt

Cited by 7 publications

References 25 publications

Color centers in NaCl by hybrid functionals

Color centers in NaCl by hybrid functionals

Periodic calculations of excited state properties for solids using a semiempirical approach

Mobility of F Centers in Alkali Halides

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