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Migration of positively charged defects in alpha-quartz


Laino, T; Donadio, D; Kuo, I F W (2007). Migration of positively charged defects in alpha-quartz. Physical Review. B, Condensed Matter and Materials Physics, 76(19):195210.

Abstract

We apply a quantum-mechanics/molecular-mechanics (QM/MM) scheme to simulate the migration of charged defects in alpha-quartz. A QM/MM framework together with a self-interaction correction (SIC) scheme was used to investigate the stability of the charged dimer defect and the E'(1) center in alpha-quartz. The use of a SIC scheme makes the charged dimer center unstable in alpha-quartz, in agreement with the experimental failure of identifying this defect, while the effects of the correction of the self-interaction error on the E-1(') center are negligible. Moreover, we conjecture that by overcoming a low energy barrier, the puckering mechanism (ideally heading from the charged dimer defect to the E'(1) center in SIC-free calculations) can be reiterated allowing the drift of the positive charge localized on an overcoordinated oxygen atom. This process can be regarded as an important channel of structural reorganization of oxygen deficient silica in the presence of strong polarizing electric fields.

We apply a quantum-mechanics/molecular-mechanics (QM/MM) scheme to simulate the migration of charged defects in alpha-quartz. A QM/MM framework together with a self-interaction correction (SIC) scheme was used to investigate the stability of the charged dimer defect and the E'(1) center in alpha-quartz. The use of a SIC scheme makes the charged dimer center unstable in alpha-quartz, in agreement with the experimental failure of identifying this defect, while the effects of the correction of the self-interaction error on the E-1(') center are negligible. Moreover, we conjecture that by overcoming a low energy barrier, the puckering mechanism (ideally heading from the charged dimer defect to the E'(1) center in SIC-free calculations) can be reiterated allowing the drift of the positive charge localized on an overcoordinated oxygen atom. This process can be regarded as an important channel of structural reorganization of oxygen deficient silica in the presence of strong polarizing electric fields.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2007
Deposited On:22 Mar 2009 17:20
Last Modified:05 Apr 2016 12:27
Publisher:American Physical Society
ISSN:1098-0121
Publisher DOI:10.1103/PhysRevB.76.195210
Permanent URL: http://doi.org/10.5167/uzh-3452

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