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Topological control of water reactivity on glass surfaces: evidence of a chemically stable intermediate phase (proof)

Summary

The research motivation is that glass topology—variations in bond constraints across the network—should modulate hydrolysis propensity at hydrated surfaces, with implications for long-term weathering and engineering of silicate interfaces. The published letter’s opening experimental protocol section states that bulk sodium silicate glasses were first generated for a nominal 70SiO₂·30Na₂O composition using the Teter potential in a periodic cell sized to match the experimental mass density before surfaces were prepared for subsequent reactive simulations. This file is the author proof PDF for the J. Phys. Chem. Lett. communication on topological control of water reactivity on sodium silicate glass surfaces (DOI 10.1021/acs.jpclett.9b01275). The study combines melt/quench molecular dynamics with a Teter-type potential to generate ~70 SiO₂·30 Na₂O glass, cleaved surfaces, and ReaxFF Na/Si/O/H simulations of water interactions mapped against a rigidity percolation-style constraint density metric. DFT checks support key conclusions summarized in the letter. The version-of-record PDF used for stable pagination and figures is on [[2019wilkinson-j-phys-chem-topological-control]] (papers/Wilkinson_JPCL_2019_water_reactivity_SiO2.pdf).

Methods

Glass formation uses LAMMPS with the Teter potential in PBC cells (see letter) to produce 70 SiO₂·30 Na₂O glass for subsequent cleaving; NVE melt/NVT quench and NPT 1 atm stages mirror 2019wilkinson-j-phys-chem-topological-control, with thermostat/barostat lines copied from the VOR, not this proof. ReaxFF interfacial molecular dynamics then evaluates water binding energies vs local constraint density on the exposed slab; duration and loadings of H₂O are in the VOR/SI. N/A on this page for exact fs timestep and temperature-resolved sampling lengths in ps/ns (target K ranges for melt/quench are in the VOR Methods)—proof pagination may not match. Barostat usage: follow the VOR (post-melt NPT at 1 atm; ReaxFF exposure may be NVT). Electric field: N/A. Enhanced sampling: N/A unless the SI states otherwise.

Findings

Coupling continuum rigidity theory intuition with atomistic ReaxFF maps lets the authors correlate local constraint density with energy-resolved water interaction strengths reported in the letter. The authors argue that surface patches near isostatic rigidity (~three constraints per atom in their mapping) exhibit reduced water-driven reactivity compared with under- or over-constrained regions, interpreting the result as evidence for a topologically stabilized intermediate surface regime. Quantitative thresholds and figure panels appear in the VOR PDF.

Limitations

Environmental water coverage and pH effects beyond the simulated vapor–surface contact are not the focus of the abstract-level summary; consult the full letter for scope. Glass topology metrics depend on cutoffs used to define constraints; sensitivity analyses in the SI (VOR) should be consulted before exporting quantitative thresholds into other silicate projects. Proof PDFs can differ in pagination, line breaks, and minor copy from the issue PDF. Use [[2019wilkinson-j-phys-chem-topological-control]] for external citations.

Confidence rationale: med—duplicate proof; science on VOR page.

Reader notes (navigation)

Glass–water ReaxFF is a recurring theme in the group corpus; this letter belongs alongside wear and geochemical silicate notes under theme hubs for oxides and water.