On a proposed radiation‐induced polaronic hole in silicon dioxide

Rao, P. Sambasiva; McEachern, R. J.; Weil, John A.

doi:10.1002/jcc.540120216

Cited by 13 publications

(2 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The cluster dangling bonds have been saturated by H atoms, a commonly used technique to ''embed'' clusters of semiconducting or insulating materials. [21][22][23][24][25][26][27][28][29][30][31] The positions of the cluster atoms were initially fixed to those of ␣-quartz derived from x-ray diffraction data at 94 K. 32 The embedding H atoms were fixed at a distance of 0.96 Å from the respective O atoms along the O-Si directions of ␣-quartz. The position of all the Si and O atoms of the cluster has been fully optimized.…”

Section: A Cluster Models and Wave Functionsmentioning

confidence: 99%

Ab initioformation energies of point defects in pure and Ge-dopedSiO2

1997

View full text Add to dashboard Cite

We have studied by means of ab initio calculations including electron correlation and cluster models the formation energies of a series of defects in bulk SiO 2 and in silica glasses containing Ge impurities. The defects considered include oxygen vacancies, wSi-Siw, peroxyl linkages, wSi-O-Siw, peroxyl radicals,The corresponding analogs with Ge atoms replacing the network Si atoms have also been considered. We found that the formation of a single oxygen vacancy, defined as the energy required to remove and bring to infinity a neutral O atom, is 8.5 eV. This is consistent with the most recent thermodynamic estimates. The stability as well as the geometry of the other defects is discussed. It is shown that in the presence of Ge impurities the formation of oxygen deficient centers occurs at a lower energy cost.

show abstract

Section: A Cluster Models and Wave Functionsmentioning

confidence: 99%

Ab initioformation energies of point defects in pure and Ge-dopedSiO2

1997

View full text Add to dashboard Cite

show abstract

“…This shortcoming could be overcome by means of quantum chemical methods. In recent years, these methods, making no a priori assumptions about the electronic density distribution in the pcrfcct solid or in the vicinity of the defect under study (and often not even about the ionic relaxation in the surrounding lattice), have been used many times for the investigation of spectroscopic properties of point defects in wide-gap insulating solids [24][25][26][27][28][29][30][31][32][33][34][35] and have demonstrated their high reliability.…”

mentioning

confidence: 99%

Quantum chemical simulations of hole self-trapping in corundum

Jacobs

Kotomin

Stashans

et al. 1992

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Microscopic quantum chemical calculations and simulations based on atom-atom potentials have been undertaken for hole self-trapping in pure corundum ( alpha -Al2O3) crystals. A comparison of different modes of ionic relaxation during hole trapping has shown that the inward Jahn-Teller 40% displacement of two O ions accompanied by the 20% outward displacement of the two nearest Al ions is energetically the most favourable. Eighty per cent of the hole density is concentrated on these two O ions, thus confirming that a small-radius two-site polaron model similar to that for alkali halides (the VK centre), is applicable here. The calculated absorption energy of the STH (2.9 eV) is close to that observed experimentally.

show abstract

Ab initio calculations on CO₄ centers in silicon dioxide

1991

Self Cite

View full text Add to dashboard Cite

Ab initio SCF-MO Hartree-Fock calculations were performed using the STO-3G, 6-31G, and 6-31G* basis sets to model hypothetical substitutional carbon impurities in silicon dioxide. We utilized nine-atom clusters, [C(OH),]qt, with charge number qt = 0 and + 1. The positions of the C and 0 atoms were varied to achieve minimum total energies, while the fured protons served to simulate the rigid crystal surroundings. In the optimized configuration of the neutral cluster, the C-0 bond lengths are appreciably longer than typical C-0 bonds, indicating relatively weak bonds for a carbon impurity at a sipcon site. For comparison, the relative positions of all nine atoms in the [C(OH),]O model were allowed to vary. This unconstrained model yielded more normal bond lengths and was lower in energy than the fured-proton model by 6.80 eV with the 6-31G* basis set. The free-H model compared favorably with the x-ray diffraction data for an analogous orthocarbonate. Our results are in concert with the lack of reports of any substitutional carbon impurity in a-quartz. In the fured-H models, the twofold local symmetry was found to be retained when qt is 0 but not when qt is + 1. For the latter ion, the unrestricted H-F calculations indicate that this paramagnetic center has its spin population almost entirely on one oxygen ion and is high in energy (5.31 eV with 631G) compared to the diamagnetic neutral one. Conclusions reached with the nine-atom clusters were confirmed by a series of calculations on the extended model [C(0SiH3)Jo.

show abstract

On a proposed radiation‐induced polaronic hole in silicon dioxide

Cited by 13 publications

References 53 publications

Ab initioformation energies of point defects in pure and Ge-dopedSiO2

Ab initioformation energies of point defects in pure and Ge-dopedSiO2

Quantum chemical simulations of hole self-trapping in corundum

Ab initio calculations on CO₄ centers in silicon dioxide

Contact Info

Product

Resources

About

On a proposed radiation‐induced polaronic hole in silicon dioxide

Cited by 13 publications

References 53 publications

Ab initioformation energies of point defects in pure and Ge-dopedSiO2

Ab initioformation energies of point defects in pure and Ge-dopedSiO2

Quantum chemical simulations of hole self-trapping in corundum

Ab initio calculations on CO4 centers in silicon dioxide

Contact Info

Product

Resources

About

Ab initio calculations on CO₄ centers in silicon dioxide