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Non-adiabatic effects during the dissociative adsorption of O_(2) at Ag(111)? A first-principles divide and conquer study



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Goikoetxea, Itziar and Beltrán Finez, Juan Ignacio and Meyer, Jörg and Juristi, Iñaki and Aducin, Maite and Reuter, Karsten (2012) Non-adiabatic effects during the dissociative adsorption of O_(2) at Ag(111)? A first-principles divide and conquer study. New journal of physics, 14 . ISSN 1367-2630

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Official URL: http://dx.doi.org/10.1088/1367-2630/14/1/013050



We study the gas-surface dynamics of O_(2) at Ag(111) with the particular objective to unravel whether electronic non-adiabatic effects are contributing to the experimentally established inertness of the surface with respect to oxygen uptake. We employ a first-principles divide and conquer approach based on an extensive density-functional theory mapping of the adiabatic potential energy surface (PES) along the six O_(2) molecular degrees of freedom. Neural networks are subsequently used to interpolate these grid data to a continuous representation. The low computational cost with which forces are available from this PES representation allows then for a sufficiently large number of molecular dynamics trajectories to quantitatively determine the very low initial dissociative sticking coefficient at this surface. Already these adiabatic calculations yield dissociation probabilities close to the scattered experimental data. Our analysis shows that this low reactivity is governed by large energy barriers in excess of 1.1 eV very close to the surface. Unfortunately, these adiabatic PES characteristics render the dissociative sticking a rather insensitive quantity with respect to a potential spin or charge non-adiabaticity in the O_(2)–Ag(111) interaction. We correspondingly attribute the remaining deviations between the computed and measured dissociation probabilities primarily to unresolved experimental issues with respect to surface imperfections.

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© IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. We thank Professor A Kleyn for useful and clarifying discussions on their molecular beam experiments. The work of IG has been supported by the Spanish Research Council (CFM-CSIC, grant numbers JAE-Pre 08 0045 and 2010ESTCSIC-02167). Funding from the Deutsche Forschungsgeinschaft (RE 1509/7-1) is gratefully acknowledged. MA and IJ also acknowledge the Spanish Ministerio de Ciencia e Innovación (grant no. FIS2010-19609-C02-02).

Uncontrolled Keywords:Potential-energy surfaces; 6-dimensional quantum dynamics; Nondissociative sitcking; Classical dynamics; Oxygen-adsorption; Silver surfaces; H-2; Desorption; Chemisorption; Networks.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:31379
Deposited On:27 Jul 2015 08:03
Last Modified:10 Dec 2018 14:58

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