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Keal TW, Sherwood P, Dutta G, Sokol AA, Catlow CRA. Characterization of hydrogen dissociation over aluminium-doped zinc oxide using an efficient massively parallel framework for QM/MM calculations. Proc Math Phys Eng Sci 2011. [DOI: 10.1098/rspa.2010.0613] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A task-farm parallelization framework has been implemented in the ChemShell computational chemistry environment to provide a facility for parallelizing common chemical calculations, including finite-difference Hessian evaluation, the nudged elastic band method for reaction path optimization, and population-based methods for global optimization. The optimization methods are provided by a parallel interface to the DL-FIND optimization library. As ChemShell can already exploit parallel external programs for energy and gradient evaluations, the new methods result in a two-level approach to parallelization that gives significantly improved performance for massively parallel calculations. For typical systems, speed-up factors of five to eight times have been observed compared with non-task-farmed calculations. The task-farming version of ChemShell has been used to study the heterolytic dissociation of a hydrogen molecule over a polar oxygen-terminated surface of aluminium-doped zinc oxide using an embedded cluster hybrid QM/MM approach. We calculate a 42 kcal mol
−1
heat of reaction and a 30 kcal mol
−1
activation energy, which is equivalent to a high backward reaction barrier of 72 kcal mol
−1
per H
2
molecule, in close agreement with temperature programmed desorption experiments. The dissociation path includes a stable intermediate comprising a hydride ion in an oxygen vacancy and physisorbed atomic hydrogen.
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Affiliation(s)
- Thomas W. Keal
- Computational Science and Engineering Department, STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK
| | - Paul Sherwood
- Computational Science and Engineering Department, STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK
| | - Gargi Dutta
- Department of Chemistry, University College London, Kathleen Lonsdale Materials Chemistry, 20 Gordon Street, London WC1H 0AJ, UK
| | - Alexey A. Sokol
- Department of Chemistry, University College London, Kathleen Lonsdale Materials Chemistry, 20 Gordon Street, London WC1H 0AJ, UK
| | - C. Richard A. Catlow
- Department of Chemistry, University College London, Kathleen Lonsdale Materials Chemistry, 20 Gordon Street, London WC1H 0AJ, UK
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