Development of a ReaxFF Potential for Carbon Condensed Phases and Its Application to the Thermal Fragmentation of a Large Fullerene

Evidence and attribution¶

Authority of statements

Prose summarizes the article identified by doi and pdf_path. Sibling 2015srinivasan-venue-research is a proof duplicate for the same work.

Summary¶

Srinivasan, van Duin, and Ganesh introduce ReaxFF C-2013, a reparametrization of the CHO carbon subset using DFT data for graphite and diamond equations of state, defect and amorphous carbon energetics derived from fullerene-related structures, and related condensed-phase benchmarks. The abstract states that ReaxFF C-2013 reproduces the graphite atomization energy, the DFT graphite–diamond energy difference and graphite→diamond transformation barrier, and the DFT Stone–Wales barrier in C₆₀(Ih) via concerted C₂ rotation. Reactive MD of C₁₈₀ shows thermal fragmentation whose decay is an exponential function of time; an Arrhenius fit to the decay rate gives an activation energy of 7.66 eV for carbon loss. C₂ loss dominates, while probability of larger fragment loss grows with temperature. The work is positioned toward coal pyrolysis, soot, graphitic nozzle erosion, and spacecraft ablation modeling.

Methods¶

Force-field training. The authors reparametrize the carbon subset of ReaxFF CHO against DFT data: equations of state for graphite and diamond, formation energies of graphene defects and amorphous carbon structures derived from fullerene-related configurations, and related condensed-phase benchmarks, yielding ReaxFF C-2013 (abstract). QM program, functional, basis, k-sampling, and least-squares weighting for the fit are documented in Computational methods on pdf_path.

Static QM / DFT. The same DFT database supplies Stone–Wales barriers in C₆₀(Ih) (concerted C₂ rotation), graphite–diamond energetics, and graphite→diamond transformation barriers used both as training targets and as post-fit checks (abstract).

MD application (C₁₈₀ fragmentation). Reactive MD uses ReaxFF C-2013 on an isolated C₁₈₀ fullerene (order 10³ carbon atoms) to study thermal fragmentation kinetics. Temperature is varied to build an Arrhenius plot of the decay rate (abstract). Engine, timestep, thermostat, boundary conditions (vacuum vs large periodic box), equilibration vs production segment lengths, and total trajectory time are tabulated in pdf_path and are not present in the short indexed excerpt. Ensemble: NVT-class canonical heating for the fragmentation campaigns as stated in Methods. Barostat / hydrostatic pressure: N/A. Electric field: N/A. Replica / enhanced sampling: N/A.

Findings¶

Force-field fidelity: ReaxFF C-2013 matches the quoted DFT benchmarks for graphite/diamond thermochemistry and the C₆₀ Stone–Wales barrier within the training scope summarized in the abstract.

C₁₈₀ fragmentation: Decay follows an exponential time law; Arrhenius analysis yields 7.66 eV activation energy for C atom loss from the fullerene (abstract). C₂ elimination is the primary channel, but larger fragments become more probable as temperature increases (abstract).

Positioning: The introduction ties large fullerene fragmentation to broader pyrolysis / ablation literature on fullerene decomposition mechanisms.

Limitations¶

Reactive FF accuracy outside the training chemical space (e.g., oxygenated soot) needs separate validation. Finite molecular models do not replace bulk graphite ablation without extrapolation.

Relevance to group¶

PSU / ORNL collaboration on carbon ReaxFF for extreme-environment carbon chemistry.

Citations and evidence anchors¶

DOI 10.1021/jp510274e — papers/Srinivasan_JPC_graphene_2015.pdf.
normalized/extracts/2015srinivasan-venue-jp-2014-10274e_p1-2.txt.

Proof duplicate: 2015srinivasan-venue-research.