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Dynamics of the Dissociation of Hydrogen on Stepped Platinum Surfaces Using the ReaxFF Reactive Force Field

Ludwig, Jeffery and Vlachos, Dionisios G. and van Duin, Adri C. T. and Goddard, William A., III (2006) Dynamics of the Dissociation of Hydrogen on Stepped Platinum Surfaces Using the ReaxFF Reactive Force Field. Journal of Physical Chemistry B, 110 (9). pp. 4274-4282. ISSN 1520-6106. doi:10.1021/jp0561064.

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The dissociation of hydrogen on eight platinum surfaces, Pt(111), Pt(100), Pt(110), Pt(211), Pt(311), Pt(331), Pt(332), and Pt(533), has been studied using molecular dynamics and the reactive force field, ReaxFF. The force field, which includes the degrees of freedom of the atoms in the platinum substrate, was used unmodified with potential parameters determined from previous calculations performed on a training set exclusive of the surfaces considered in this work. The energetics of the eight surfaces in the absence of hydrogen at 0 K were first compared to previous density functional theory (DFT) calculations and found to underestimate excess surface energy. However, taking Pt(111) as a reference state, we found that the trend between surfaces was adequately predicted to justify a relative comparison between the various stepped surfaces. To assess the strengths and weaknesses of the force field, we performed detailed simulations on two stepped surfaces, Pt(533) and Pt(211), and compared our findings to published experimental and theoretical results. In general, the absolute magnitude of reaction rate predictions was low, a result of the force field's tendency to underpredict surface energy. However, when normalized, the simulations show the correct linear scaling with incident energy and angular dependence at collision energies where a direct dissociation mechanism is observed. Because ReaxFF includes all degrees of freedom in the substrate, we carried out simulations aimed at understanding surface-temperature effects on Pt(533). On the basis of the results on Pt(533)/Pt(211), we studied the reaction of hydrogen at normal incidence on all eight surfaces in a range of energies where we anticipated the force field to give reasonable qualitative trends. These results were subsequently fit to a simple linear model that predicts the enhanced reactivity of surfaces containing 111-type atomic steps versus 100-type atomic steps. This model provides a simple framework for predicting high-energy/high-temperature kinetics of complex surfaces not vicinal to Pt(111).

Item Type:Article
Related URLs:
URLURL TypeDescription Information
van Duin, Adri C. T.0000-0002-3478-4945
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2006 American Chemical Society. Received 24 October 2005. Published online 7 February 2006. Published in print 1 March 2006. We acknowledge partial support of this research by the U. S. Department of Energy, under award no. DE-FG02-03ER15468. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-03ER15468
Issue or Number:9
Record Number:CaltechAUTHORS:20170711-133901699
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Official Citation:Dynamics of the Dissociation of Hydrogen on Stepped Platinum Surfaces Using the ReaxFF Reactive Force Field Jeffery Ludwig, Dionisios G. Vlachos, Adri C. T. van Duin, and William A. Goddard, III The Journal of Physical Chemistry B 2006 110 (9), 4274-4282 DOI: 10.1021/jp0561064
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78955
Deposited By: Ruth Sustaita
Deposited On:11 Jul 2017 21:01
Last Modified:15 Nov 2021 17:44

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