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Deuterium uptake and sputtering of simultaneous lithiated, boronized, and oxidized carbon surfaces irradiated by low-energy deuterium (publisher proof)

Publisher proof PDF (layout/author-query banner) for the J. Appl. Phys. study of low-energy D bombardment of Li–B–C–O amorphous carbon surfaces with ReaxFF extended for B and Li. Scientific content matches 2018f-j-dom-nguez-guti-r-journal-of-a-deuterium-uptake; prefer that page for pagination and figure citation.

Summary

Reactive MD with ReaxFF (EEM charges, LAMMPS) quantifies D retention and sputtering for plasma-facing carbon conditioned with Li, B, and O, comparing to new experiments on B–C–O–D systems. The work interprets how oxygen and mixed conditioning tune erosion vs retention of D at fusion-relevant low impact energies. Tokamak and stellarator first walls see low-Z carbon tiles and mixed-material coatings where lithium injectors, boronization, and oxygen recycling all change near-surface stoichiometry; matching simulation to beam or plasma exposure data therefore requires chemically specific ReaxFF extensions for Li–B–C–O–D rather than pure hydrocarbon carbon models.

Methods

Same protocol as 2018f-j-dom-nguez-guti-r-journal-of-a-deuterium-uptake (Sec. II in the VOR PDF): ReaxFF Li–B–C–O–D trained vs NWChem PBE0/6-31G benchmarks; ~400-atom surface cells (~1.8 nm lateral, ~2.0 nm depth); melt/quench + 300 K Langevin preparation; D impacts at 5 eV (retention) and 5 eV / 30 eV (sputtering) with 50 ps spacing, 20 ps cascade + 20 ps rethermalization + 10 ps relax; N = 15000 impacts for production statistics. This slug’s PDF is the proof variant—typography may differ from the version of record*.

MD packaging: Simulations are run in LAMMPS with ReaxFF on ~400-atom slab supercells under 3D PBC. Each impact cycle uses ~20 ps NVE-like cascade evolution, ~20 ps rethermalization toward 300 K with canonical sampling as in Sec. II, then ~10 ps relaxation—durations on the picosecond scale between impacts. The timestep is specified in Sec. II of the version-of-record PDF on 2018f-j-dom-nguez-guti-r-journal-of-a-deuterium-uptake. N/A — NPT barostat and N/A — fixed hydrostatic pressure targets for the documented bombardment recipe (constant-volume slab protocol).

Findings

  • Oxygen participates in D bonding pathways across compositions; combined experiment + simulation highlight retention mechanisms in B–Li–C–O mixtures.
  • Boron can reduce carbon erosion vs reference surfaces; lithium modulates oxygen surface content under D bombardment in the regimes discussed.
  • Mixed Li + B + O conditioning acts as a knob for erosion/retention trade-offs relevant to fusion PFC materials. The companion version-of-record page (2018f-j-dom-nguez-guti-r-journal-of-a-deuterium-uptake) should be cited for final figure labels and pagination when preparing benchmark questions; this proof slug exists mainly for manifest provenance.

Limitations

Proof PDF may lack final pagination; classical reactive models omit explicit electronic sputtering. Full methodological tables: 2018f-j-dom-nguez-guti-r-journal-of-a-deuterium-uptake.

Magnetic field effects, impurity atoms beyond Li–B–C–O–D, and long-time diffusive mixing in tokamak tiles are outside the single-impact statistics emphasized in the Sec. II protocol; upscaling to reactor wall lifetimes requires multiscale models layered on top of these ReaxFF cross sections.

Relevance to group

van Duin coauthorship on ReaxFF for fusion boundary plasmas; this file records proof-stage corpus provenance.

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