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Type: Artigo
Title: On the trapping of bjerrum defects in ice Ih: the case of the molecular vacancy
Author: Koning, Maurice de
Antonelli, Alex
Abstract: We present a density-function theory (DFT) study of Bjerrum-defect trapping centers involving the molecular vacancy in ice Ih. As a first step, we compute the intrinsic migration barrier to D-defect motion using the nudged elastic band (NEB) method and find them to be of the same order of magnitude as the energy barriers involving intrinsic L-defect motion. This finding suggests that intrinsic mobility factors cannot explain the experimentally observed inactivity of D defects, supporting the idea that D defects are trapped at other lattice-defect sites. Next we study the defect complexes formed by the combination of isolated D and L defects with a molecular vacancy. The corresponding geometries show that the formation of these aggregates significantly reduces elastic distortions that are present in isolated Bjerrum defects. An analysis of the energetics involved in the formation of both defect complexes reveals a significant binding energy, indicating that the molecular vacancy represents a strong trapping center for Bjerrum defects. On the other hand, the fact that there is no difference between the absolute values of the binding energies for both D and L defects suggests that the vacancy affects both species of Bjerrum defects in a similar fashion, possibly ruling out the vacancy trapping centers as an explanation for the experimentally observed inactivity of D defects.
Subject: Gelo hexagonal
Teoria do funcional de densidade
Energia de ligação
Country: Estados Unidos
Editor: American Chemical Society
Citation: Journal Of Physical Chemistry B. Amer Chemical Soc, v. 111, n. 43, n. 12537, n. 12542, 2007.
Rights: fechado
Identifier DOI: 10.1021/jp075661y
Date Issue: 2007
Appears in Collections:IFGW - Artigos e Outros Documentos

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