Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation
Summary¶
This ingest tracks papers/Yoon_ACSNano_online.pdf for Yoon et al., ACS Nano, DOI 10.1021/acsnano.6b03036: ReaxFF MD of noble-gas ion irradiation of graphene with annealing, validated by aberration-corrected STEM and HIM. The article argues dose, ion energy, and ion species jointly set defect motifs and vacancy coalescence into nanopores, using nuclear-collision-focused MD that neglects electronic stopping with literature justification for graphene. This online PDF is a duplicate corpus path relative to the VOR record [[2016yoon-venue-nn6b03036]].
Methods¶
Same DOI as [[2016yoon-venue-nn6b03036]]. LAMMPS ReaxFF on periodic graphene ~52 × 40 Ų (large carbon atom count in the published supercell) receives 25 keV noble-gas impacts in ~30 × 20 Ų. NVE cores use 0.005–0.02 fs timesteps; edge regions stay at 300 K via thermostat coupling described in the article. Dose rates space successive cascades. He\(^+\) series use 1500 K / 25 ps then 2000 K / 1.25 ns annealing; heavier ions add 1500 K plus 3000 K annealing (the 3000 K segment duration is not recovered from the Methods text checked here). Barostat, electric fields, and replica / enhanced sampling are not used on these irradiation legs. Hydrostatic pressure is not servo-controlled on these legs (N/A — fixed-area NVE core; no NPT pressure target in the summarized protocol). HIM and 60 kV STEM protocols sit under Experimental methods and details.
Findings¶
Annealing after cumulative impacts drives vacancy coalescence into nanopores with strong dose and ion-mass sensitivity, i.e. heavier ions and higher dose trend toward larger pores and more surrounding disorder in the simulations. STEM experiment comparisons show broadly consistent dose trends while the text flags impurities, contamination, and metal-catalyzed edge chemistry as limitations on one-to-one agreement. Sensitivity to dose rate (simulated vs experimental beam schedules) is discussed as an authored caveat, alongside model uncertainty in the reactive MD treatment. Defect statistics (STW vs monovacancy prevalence by ion species) and sputtering-style metrics are reported in the article relative to prior literature benchmarks. For pagination and figure-level claims, prefer the version-of-record PDF [[2016yoon-venue-nn6b03036]] over this duplicate pdf_path.
Limitations¶
Prefer [[2016yoon-venue-nn6b03036]] for pagination when citing the VOR PDF; duplicate corpus PDFs can differ in pagination. Electronic stopping and electronic excitation are neglected in the nuclear-collision framing described in the opening pages—consistent with cited precedents for graphene but not universally valid for all 2D materials.
Relevance to group¶
van Duin collaboration with ORNL on 2D carbon radiation effects.
Citations and evidence anchors¶
- DOI:
https://doi.org/10.1021/acsnano.6b03036(papers/Yoon_ACSNano_online.pdf).