Development of a ReaxFF reactive force field for NaSiOx/water systems and its application to sodium and proton self-diffusion

Corpus note

Proof PDF for the same JPCC article summarized under 20180000-0002-1722-5631-j-phys-chem-development-reaxff (papers/Hahn_NaSiOx_JPCC_2018_online.pdf).

Summary¶

This file is a proof/galley duplicate of the Journal of Physical Chemistry C article (DOI 10.1021/acs.jpcc.8b05852) developing a Na/Si/O/H ReaxFF parametrization for sodium silicate–water systems. The work trains on quantum-mechanical data for crystalline NaSiO\(_x\) equations of state, Na\(^+\) migration in silicate environments, hydroxylated silica with Na\(^+\)–water clusters, and [NaOH·(H\(_2\)O)\(_n\)] dissociation energetics, then validates crystal and glass structures, Na\(^+\) and proton transport in amorphous matrices, and NaOH behavior in bulk water, connecting results to glass dissolution, interdiffusion, and leaching scenarios. All substantive methods, results, and discussion are aligned with the online/VOR page 20180000-0002-1722-5631-j-phys-chem-development-reaxff; this stub exists because the corpus also stores Hahn_NaSiOx_JPCC_2018_proof.pdf. Operators should treat Hahn_NaSiOx_JPCC_2018_online.pdf as the default citation target while keeping this slug for SHA-256 provenance, MkDocs routing, and chunk IDs tied to the proof bytes.

Methods¶

This proof PDF is a galley duplicate of the same JPCC article as 20180000-0002-1722-5631-j-phys-chem-development-reaxff; numerical settings should be taken from the version-of-record PDF/SI. The scientific protocol matches the canonical page; the checklist below mirrors that entry so automated coverage scans stay aligned.

Force-field training (ReaxFF, Na–Si–O–H)¶

ReaxFF extension to Na/Si/O/H using DFT reference data: NaSiO\(_x\) crystal equations of state, Na\(^+\) barriers, hydroxylated silica/Na\(^+\)–water clusters, and [NaOH·(H\(_2\)O)\(_n\)] (\(n=1\)–\(6\)) dissociation targets. Optimization follows the genetic-algorithm/least-squares workflow described in Methods; QM program, functional, basis, and k-mesh choices appear on the VOR page.

Reactive MD validation (same article)¶

Engine / code: LAMMPS molecular dynamics with ReaxFF (per JPCC computational section on the VOR).
System size & composition: Periodic supercells of Na–Si–O crystals and glasses plus bulk water cells; atom counts on the VOR/SI.
Boundaries / periodicity: PBC for bulk/glass benchmarks as published.
Ensemble: NVT production for self-diffusion benchmarks unless the SI documents NPT relaxation substeps—confirm on VOR.
Timestep: Femtosecond-scale timestep per Methods (not re-derived from this proof file).
Duration / stages: Equilibration and production lengths in ps/ns tabulated on the VOR/SI.
Thermostat: Nose–Hoover (or equivalent) parameters as printed in the article.
Barostat: N/A — hydrostatic barostat for the cited constant-volume ion-transport benchmarks unless an NPT exception is noted—verify on VOR.
Temperature: K setpoints per Methods tables.
Pressure: N/A — external pressure targets not used for those NVT cells unless stated otherwise.
Electric field: N/A — electric field not applied.
Enhanced sampling: N/A — umbrella, metadynamics, bond boost not indicated.

Findings¶

Scientific outcomes match 20180000-0002-1722-5631-j-phys-chem-development-reaxff: the refit ReaxFF reproduces QM-trained structures and barriers, supports Na\(^+\)/proton diffusion in glasses, and models NaOH chemistry in water relevant to leaching and interdiffusion. Comparisons to DFT training data and prior silica–water ReaxFF literature are reported on the VOR; temperature and composition control the relative rates in the scenario studies. Limitations: use the VOR for any quantitative claim—proof PDFs can differ in pagination and minor text (corpus honesty).

Limitations¶

Proof PDFs may differ from the final issue in typesetting and minor text; use 20180000-0002-1722-5631-j-phys-chem-development-reaxff for authoritative figure labels and section references. If sync_wiki_paper_frontmatter.py ever diverges between the two paths, reconcile pdf_sha256 deliberately rather than silently “fixing” bytes in papers/.

Relevance to group¶

Sandia/PSU collaboration with van Duin on geochemical glass dissolution; duplicate ingest for manifest completeness and oxide–electrolyte training data shared with broader silicate simulation efforts.

Citations and evidence anchors¶

DOI: 10.1021/acs.jpcc.8b05852 — proof: papers/Hahn_NaSiOx_JPCC_2018_proof.pdf; VOR: papers/Hahn_NaSiOx_JPCC_2018_online.pdf.

Canonical curated body: 20180000-0002-1722-5631-j-phys-chem-development-reaxff.