Electron nuclear double resonance of intrinsic and impurity centers in ionic crystals

Spaeth, J.‐M.; Koschnick, F. K.

doi:10.1016/0022-3697(91)90058-8

Cited by 45 publications

(21 citation statements)

References 252 publications

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“…As is clear from the previous section, in order to calculate the localization energy of the hole, Eloc [Eq. (6)], the energy EL of the localized hole in the perfect crystal lattice has to be carefully calculated. The following estimate for the energy EL seems to have become generally accepted [25-271; namely, that the energy EL is assumed to coincide with the "center of gravity" of the band.…”

Section: Calculation Of the Hole Localization Energymentioning

confidence: 99%

Quantum chemical simulations of hole self‐trapping in semi‐ionic crystals

Kantorovich

Stashans

Kotomin

et al. 1994

Int J of Quantum Chemistry

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A novel formalism is presented for reliable calculations of the energetics of hole self-trapping in semi-ionic solids with mixed valence bands. Unlike previous model-Hamiltonian-type approaches, it is based on self-consistent quantum chemical INDO simulations of the atomistic and electronic structure of a self-trapped hole, making no a priori assumptions about a particular form of its localization (if any). This formalism is applied to the problem of hole self-trapping in corundum crystals ( a -A1203). The hole self-trapping is found to be energetically favorable in the form of a diatomic 0 2 molecule with strong covalent bonding quite similar to the self-trapped hole (VK-center) in alkali halides. The so-called localization energy (i.e., the energy that is required to localize the Bloch-like wave packet of the free hole on the molecule, as the first stage of further trapping) is essentially less than one-half of the upper valence hand width, which is the estimate commonly used for ionic solids. 0 i994 John Wiley & Sons, Inc.

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Section: Calculation Of the Hole Localization Energymentioning

confidence: 99%

Quantum chemical simulations of hole self‐trapping in semi‐ionic crystals

Kantorovich

Stashans

Kotomin

et al. 1994

Int J of Quantum Chemistry

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“…To gain better insight into this relevant matter is certainly not easy because compounds that are similar in composition do not always display the same structure. For instance, at low temperatures, KMgF 3 and KNiF 3 perovskites are both cubic, while KMnF 3 is tetragonal. 1,2 In the same vein, there is a striking difference in the geometry of the CuCl 4 (NH 3 ) 2 2− and CuCl 4 (H 2 O) 2 2− centers formed, for example, in Cu 2+ -doped NH 4 Cl.…”

Section: Introductionmentioning

confidence: 99%

Origin of Small Barriers in Jahn–Teller Systems: Quantifying the Role of 3d–4s Hybridization in the Model System NaCl:Ni⁺

Barriuso¹,

Ortiz-Sevilla²,

Aramburu³

et al. 2013

Inorg. Chem.

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Despite its relevance, the microscopic origin of the energy barrier, B, between the compressed and elongated geometries of Jahn−Teller (JT) systems is not well understood yet because of a lack of quantitative data about its various contributions. Seeking to clear up this matter, we have carried out both periodic and cluster ab initio calculations on the model system NaCl:Ni + . This system is particularly puzzling because, according to experimental data, its barrier is much smaller than that for other d 9 and d 7 ions in similar lattices. All calculations performed on the model system lead, in fact, to values |B| ≤ 160 cm −1 , which are certainly smaller than B = 500 cm −1 derived for NaCl:M 2+ (M = Ag, Rh) or B = 1024 cm −1 obtained for KCl:Ag 2+ . As a salient feature, analysis of calculations carried out as a function of the Q θ (∼3z 2 − r 2 ) coordinate unveils the microscopic origin of the barrier. It is quantitatively proven that the elongated geometry observed for NaCl:Ni + is due to the 3d−4s vibronic admixture, which is slightly larger than the anharmonicity in the e g JT mode that favors a compressed geometry. The existence of these two competing mechanisms explains the low value of B for the model system, contrary to cases where the complex formed by d 9 or d 7 ions is elastically decoupled from the host lattice. Although the magnitude of B for NaCl:Ni + is particularly small, the tunneling splitting, 3Γ, is estimated to be below 9 cm −1 , thus explaining why the coherence is easily destroyed by random strains and thus a static JT effect is observed experimentally. As a main conclusion, the barrier in JT systems cannot be understood neglecting the tiny changes of the electronic density involved in small distortions. The present calculations reasonably explain the experimental g tensor of NaCl:Ni + , pointing out that the d−d transitions in NiCl 6 5− are much smaller than those for CuCl 6 4− and the optical electronegativity of Ni + is only around 1.

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“…[8][9][10][11][12][13][14][15][16][17][18][19][20] The CuCl 4 (NH 3 ) 2 2− unit is involved in the pure CuCl 2 (NH 3 ) 2 crystal, 8 and it is formed as an impurity center in HgCl 2 (NH 3 ) 2 10 ( Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Insulators containing CuCl4X22−(X=H
García‐Fernández
¹
,
Garcı́a-Lastra
²
,
Trueba
³

et al. 2012
Phys. Rev. B
17
5
43
0
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Electron nuclear double resonance of intrinsic and impurity centers in ionic crystals

Cited by 45 publications

References 252 publications

Quantum chemical simulations of hole self‐trapping in semi‐ionic crystals

Quantum chemical simulations of hole self‐trapping in semi‐ionic crystals

Origin of Small Barriers in Jahn–Teller Systems: Quantifying the Role of 3d–4s Hybridization in the Model System NaCl:Ni⁺

Insulators containing CuCl4X22−(X=H
García‐Fernández
¹
,
Garcı́a-Lastra
²
,
Trueba
³

et al. 2012
Phys. Rev. B
17
5
43
0
View full text Add to dashboard Cite

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Electron nuclear double resonance of intrinsic and impurity centers in ionic crystals

Cited by 45 publications

References 252 publications

Quantum chemical simulations of hole self‐trapping in semi‐ionic crystals

Quantum chemical simulations of hole self‐trapping in semi‐ionic crystals

Origin of Small Barriers in Jahn–Teller Systems: Quantifying the Role of 3d–4s Hybridization in the Model System NaCl:Ni+

Insulators containing CuCl4X22−(X=HGarcía‐Fernández1, Garcı́a-Lastra2, Trueba3 et al. 2012Phys. Rev. B175430View full textAdd to dashboardCite

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Origin of Small Barriers in Jahn–Teller Systems: Quantifying the Role of 3d–4s Hybridization in the Model System NaCl:Ni⁺

Insulators containing CuCl4X22−(X=H
García‐Fernández
¹
,
Garcı́a-Lastra
²
,
Trueba
³

et al. 2012
Phys. Rev. B
17
5
43
0
View full text Add to dashboard Cite