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Enabling Computational Design of ZIFs Using ReaxFF

Evidence and attribution

Authority of statements

Prose sections below (Summary, Methods, Findings, etc.) are curated summaries of the publication identified by doi, title, and pdf_path in the front matter above. They are not new primary claims by this wiki.

For definitive numerical values, reaction schemes, and interpretations, use the peer-reviewed article (and optional records under normalized/papers/ when present)—not this page alone.

Summary

Zeolitic imidazolate frameworks (ZIFs) increasingly require simulations that handle bond breaking/forming (melts, defects, chemical stability), beyond classical nonreactive FF applications. This paper demonstrates ReaxFF on representative ZIFs: melt–quench of ZIF-4 reproduces glassy aZIF-4 structure, density, thermal response, and pore morphology consistent with experiment and ab initio MD; ZIF-62 melting highlights ligand chemistry (benzimidazolate) effects on melting trends; ZIF-77 with electron-withdrawing substituents illustrates how electronic/steric balance shifts predicted melting and chemical stability. The overarching claim is that ReaxFF’s cost and transferability can support computational screening of disordered and defect-laden ZIF behavior.

ZIF glasses are challenging for fixed-bond force fields because linker scission and metal–linker reorganization accompany vitrification.

Methods

ReaxFF molecular dynamics (ZIF chemistry)

  • Force field / code: ReaxFF parametrization for Zn–Co–C–H–O–N ZIF chemistry from ref 38 in the article, implemented in LAMMPS; 0.25 fs timestep (normalized/extracts/2018yang-j-phys-chem-enabling-computational_p1-2.txt and the parallel proof-ingest extract for 2018yang-j-phys-chem-enabling-computational-2 align on LAMMPS usage).
  • Initial structures: crystalline ZIF-4, ZIF-62, and ZIF-77 from the CSD; equilibrated at 10 K with a Berendsen thermostat before heating.
  • Thermal protocol (overview): ZIF-4 and ZIF-62 are heated to 300 K in 2.5 ps under NPT (Nosé–Hoover thermostat/barostat), then ramped toward melting (1500 K within 12.5 ps per Methods). ZIF-77 is heated from 10 K to 900 K at the rate stated for that composition.

  • Glass formation (ZIF-4): the ZIF-4 melt is quenched to 300 K within 12.5 ps in NPT to obtain a_gZIF-4 glass.

  • Boundaries / periodicity: bulk ZIF crystals and their high-temperature melts are simulated in three-dimensional periodic supercells with LAMMPS (PBC on the CSD-derived unit cells, as standard for framework MD).

Validation and analysis

  • Comparisons target experimental glass metrics and FPMD benchmarks where cited; bond-order/coordination diagnostics track framework disordering, ligand chemistry, and melting.

  • Replica / metadynamics / applied E-field: N/A — not used in the ZIF melt–quench ReaxFF protocols summarized above.

Findings

  • ZIF-4 melt–quench: ReaxFF reproduces structure, density, thermal properties, and pore morphology of a_gZIF-4 in strong agreement with experiment and FPMD (abstract-level summary; see article for quantitative tables).
  • ZIF-62: benzimidazolate substitution shifts melting trends through the balance of electronic and steric effects noted in the abstract.
  • ZIF-77: −NO₂ substituents can lower Zn–N-linked melting trends in the ReaxFF picture, but the framework tends toward oxidation/decomposition, so it is a poor glass former—illustrating a stability vs processability trade-off.
  • Broader point: reactive MD fills a gap where AIMD is costly but nonreactive MOF force fields cannot represent bond rearrangement during melts, defects, or chemical failure—supporting screening narratives in the article.

Pair this page with MOF/ZIF theme hubs when routing questions about vitrification versus crystalline stability.

Limitations

  • Transferability across full ZIF chemical space still requires validation per family; reactive FF accuracy for complex organometallic linkers must be checked against higher-level benchmarks.

Relevance to group

Key MOF/ZIF + ReaxFF capability demonstration from the van Duin and Mauro collaboration—important for porous framework entries in the wiki.

Reader notes (navigation)

Citations and evidence anchors

  • reaxff-family
  • ZIF glasses and melt–quench reactive MD
  • Metal–organic frameworks beyond fixed-bond force fields