Lookup NU author(s): Professor Patrick Briddon
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First-principles models of the formation of H-2 on interstellar media carbonaceous grains are usually concerned with processes occurring on ideal graphenic surfaces. Until now these models are unable to explain the formation of molecular hydrogen due to the presence of absorption barriers that cannot be overcome at the low temperatures of the interstellar media. We propose an approach emphasizing the role of specific topological defects for molecular hydrogen catalysis at interstellar dust grain models. Using the nudged elastic band method combined with density-functional techniques, we obtain the full catalytic cycle for the formation of the H-2 molecule on complex carbon topologies involving the presence of pentagonal rings and C adatoms. Depending on structures, reaction paths can be barrierless or have adsorption barriers as low as 10(-3)-10(-2) eV, which might be easily overcome at the temperatures of the interstellar medium. Such low adsorption barriers indicate that specific carbon grains topological defects are preferential sites for the molecular hydrogen formation in the interstellar medium.
Author(s): Ivanovskaya VV, Zobelli A, Teillet-Billy D, Rougeau N, Sidis V, Briddon PR
Publication type: Article
Publication status: Published
Journal: Physical Review B
Print publication date: 01/12/2010
ISSN (print): 1098-0121
ISSN (electronic): 1550-235X
Publisher: American Physical Society
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