Processes at lithium-hydride/deuteride surfaces upon low energy impact of H/D
Summary¶
Plasma-facing components in magnetic fusion devices may use liquid or condensed lithium coatings to control impurity influx and hydrogen recycling. When hydrogen isotopes implant into lithium, near-surface regions approach lithium hydride stoichiometries that differ sharply from clean Li metal in their bonding, sputtering, and reflection response. This Frontiers in Physics article presents classical molecular dynamics with an extended ReaxFF model—including long-range polarization physics—to study sputtering, reflection, and particle retention when H and D impact crystalline and amorphous LiH surfaces. The abstract-level framing stresses comparison to earlier Li, Li\(_2\)O, and LiOH irradiation studies from the same collaboration so readers can interpret how hydride formation modifies low-energy collision outcomes relevant to divertor and first-wall modeling.
Within the fusion PMI storyline, near-surface LiH is a plausible hydrogen-rich endpoint when fuel implantation accumulates in lithium layers; treating LiH as distinct from bare Li matters because bonding, stopping, and erosion channels shift when H is chemically incorporated rather than only physisorbed. The galley path in the corpus mainly changes layout—primary statistics should still be taken from the published Frontiers PDF for DOI 10.3389/fphy.2023.1105194.
Methods¶
Interaction model (B)¶
ReaxFF-class reactive MD with long-range polarization extensions (see article).
Impact grid¶
H and D on LiH at 300 K; E = 1–100 eV; polar angles 0°–85° (near-normal to grazing).
Surface variants¶
Crystalline vs amorphous LiH terminations.
Analysis¶
Probabilities for reflection, sputtering, retention; energy/angle distributions of ejecta.
Corpus note¶
Galley path in-repo—confirm cells, Δt, and statistics vs VOR (DOI 10.3389/fphy.2023.1105194).
1 — MD application (atomistic dynamics)¶
Engine / code: LAMMPS with an extended ReaxFF and long-range polarization treatment (see Front. Phys.). System & composition: H and D on crystalline and amorphous LiH surfaces; E = 1–100 eV, 300 K, 0°–85° polar angle grid. Boundaries / periodicity: slab-style surface models with PBC in-plane as in the paper. Ensemble, timestep, run length, thermostat, barostat: H/D impacts are integrated with 0.25-fs-order ReaxFF timestep over 4–10 k steps per event and NVT-prepared 300 K surfaces; N/A in this page for the full NVT bath damping and per-run ps duration (see Front. Phys. VOR). Pressure, electric field in MD, enhanced sampling: N/A here; E in this study is beam kinetic energy (eV), not a macroscopic E-field.
2 — Force-field training¶
N/A — the article applies an extended LiH-compatible ReaxFF + polarization framework; re-fit protocols are described in the article rather than on this stub.
3 — Static QM¶
N/A — MD-centric bombardment and sputtering statistics.
Findings¶
LiH vs bare Li¶
LiH surfaces differ from bare Li in reflection, stopping, and sputtering under matched impacts—hydride bonding matters for recycling models.
PMI implication¶
Lithium conditioning can yield hydrided near-surface regions; LiH should be included when interpreting fuel recycling/impurity release.
Cross-reference¶
Connects to prior Li, Li\(_2\)O, LiOH bombardment work from the same collaboration—numbers in journal tables.
Readers building recycling models should treat these LiH results as complementary to [[2023krstic-j-appl-phys-detailed-studies]]: together they span oxide/hydroxide-rich versus hydride-rich lithium chemistries that can coexist depending on oxygen exposure and implanted H inventory.
Limitations¶
Galley PDFs may differ in figure numbering from final layout; proof boilerplate in some extracts is not scientific content. extraction_quality is partial for some pipeline rows—prefer papers/ PDF for primary numbers.
Relevance to group¶
A. C. T. van Duin is a co-author; ReaxFF parametrization for Li/H systems supports fusion and energy-storage adjacent lithium chemistry.