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<p>The reason for the abundance of molecular hydrogen (H<sub>2</sub>) in space remains unresolved. Here we study collision dynamics under spacelike conditions to test H<sub>2</sub> formation mechanisms where carbonaceous dust grains may have a catalytic role. Density functional theory molecular dynamics simulates atomic hydrogen capture and H<sub>2</sub> formation on the surface of buckminsterfullerene as a carbonaceous cosmic dust model. Maximally localized Wannier functions are applied to examine the electronic bonding during transition states. The fullerene surface is shown to be effective at warm (50K) and low (10K) temperatures in achieving atomic H chemisorption, potentially explaining the observed broad temperature range for efficient H<sub>2</sub> formation. We revise the Eley-Rideal mechanism and propose that both it and the Langmuir-Hinshelwood mechanism, induced by thermal hopping, contribute to bursts of H<sub>2</sub> formation during energetic events. Additionally, we show how fullerene maintains the abundance of H<sub>2</sub> in space by selectively preventing H<sub>2</sub> molecules from capture.</p>

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Ab-initio dynamic study of mechanisms for dust-mediated molecular hydrogen formation in space

  • 期刊论文

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  • 发表日期：

    2025年4月1日

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  • Yuzhen Guo,
  • David R. McKenzie

摘要

The reason for the abundance of molecular hydrogen (H2) in space remains unresolved. Here we study collision dynamics under spacelike conditions to test H2 formation mechanisms where carbonaceous dust grains may have a catalytic role. Density functional theory molecular dynamics simulates atomic hydrogen capture and H2 formation on the surface of buckminsterfullerene as a carbonaceous cosmic dust model. Maximally localized Wannier functions are applied to examine the electronic bonding during transition states. The fullerene surface is shown to be effective at warm (50K) and low (10K) temperatures in achieving atomic H chemisorption, potentially explaining the observed broad temperature range for efficient H2 formation. We revise the Eley-Rideal mechanism and propose that both it and the Langmuir-Hinshelwood mechanism, induced by thermal hopping, contribute to bursts of H2 formation during energetic events. Additionally, we show how fullerene maintains the abundance of H2 in space by selectively preventing H2 molecules from capture.