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Supporting information: effects of water on tribochemical wear of silicon oxide interfaces (ReaxFF MD study)

Summary

This corpus PDF is Supporting Information for a ReaxFF molecular dynamics study on water effects in tribochemical wear of silicon oxide interfaces (authors Yeon, van Duin, Kim in the extract). The excerpted pages document Si(100) oxidation with 400 O\(_2\) molecules between slabs at 300 K for 400 ps, reporting ~5–6 Å oxide growth consistent with prior MD, and summarize amorphous SiO\(_2\) density/RDF/angle benchmarks in tabular form in the SI, comparing ReaxFF to QM and experimental reference data. Additional NVT hydroxylation runs with 400 water molecules on oxidized Si(001) and amorphous silica slabs reach hydroxyl coverage steady state by ~750 ps according to the SI text.

Methods

The SI documents ReaxFF validation steps ahead of the parent Langmuir tribochemistry study. Oxidation sanity check: 400 O\(_2\) molecules between two Si(100) slabs in a 3D periodic supercell, 300 K, 400 ps of molecular dynamics, giving ~5–6 Å oxide thickness consistent with prior MD cited as [1] in the SI—barostat / controlled pressure: N/A — not stated for this oxidation box (constant-cell 300 K run as described). Amorphous silica: Table S1 compares ReaxFF to QM/experiment for bulk density (2.15 vs 2.2 g cm\(^{-3}\)), first Si–O RDF peak (1.65 vs 1.62 Å), Si–O–Si angle (152.1° vs 144°), and O–Si–O angle (110° vs 109.5°) on an annealed SiO\(_2\) slab (500 K NVT context in the SI). Hydroxylation: NVT runs with 400 H\(_2\)O on oxidized Si(001) and amorphous SiO\(_2\) (Figure S2) reach hydroxyl coverage near steady state by ~750 ps per the SI narrative. Integration package for any MD shown here: N/A — the SI pages summarized for this slug do not name the MD engine (only ReaxFF as the model). Shear, normal load, tribo cell geometry, timestep, and thermostat damping for wear production runs are likewise N/A — not on the short excerpt—use papers/Yeon_Langmuir_2016_SI.pdf in full plus the parent article for those parameters.

Findings

Together, the SI excerpts support using this Si/O/H ReaxFF setup for subsequent tribochemical work: ~5–6 Å oxide after 400 ps / 300 K with 400 O\(_2\) between Si(100) slabs tracks prior MD cited in the SI; Table S1 shows ReaxFF bulk and angular/RDF metrics for annealed SiO\(_2\) close to QM/experiment references; and hydroxyl coverage on oxidized Si(001) and amorphous SiO\(_2\) plateaus near 750 ps for 400 water molecules. Wear-rate or friction conclusions, sensitivity sweeps, and bibliographic DOI are not asserted from this SI-only slug—see the parent Langmuir article (doi: null here reflects the SI ingest).

Limitations

  • This slug is SI-only; the main article claims, figures, and tribowear conclusions are not in the p1–2 extract.
  • Manifest paper_id uses 2015kim-venue-paper while the filename references Yeon_Langmuir_2016_SI.pdf; treat metadata as corpus registration quirks until reconciled.
  • Langmuir tribochemistry studies often include load histories and counterface roughness not visible in the oxidation validation excerpt alone.

Relevance to group

Adri van Duin is a co-author; the SI documents Si/O/H ReaxFF validation steps underpinning tribochemistry and silica–water interface studies from the group’s collaborations.

Citations and evidence anchors

  • No DOI present in the SI extract pages captured here; anchor via pdf_path until linked to the parent article record.