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Using C-DFT to develop an e-ReaxFF force field for acetophenone radical anion (publisher proof PDF)

Corpus PDF role

AIP author proof / query PDF. Full typeset article text and figures for DOI 10.1063/5.0064705 are on 2021penrod-j-chem-phys-using-c-dft (Penrod_Burgess_JCP_Acetophenon_eReaxFF_2021.pdf). This slug’s extraction_quality reflects proof layout.

Summary

Cross-linked polyethylene (XLPE) insulation for high-voltage cables can release acetophenone as a by-product of peroxide curing; the molecule has favorable electron affinity, motivating reactive simulations of its radical anion in degradation chemistry. e-ReaxFF extends ReaxFF with explicit electronic degrees of freedom for charge-localized states. Starting from the 2021 Akbarian e-ReaxFF parameterization oriented toward XLPE chemistry, this work uses constrained DFT (C-DFT) to place the excess electron on each atomic center of acetophenone in turn, collects geometry-optimized energies into the e-ReaxFF training set, and iteratively refits until the force field reproduces the C-DFT targets. The authors compare equilibrium populations from energy-minimized structures across temperatures and run MD to compare e-ReaxFF electronic distributions to unconstrained DFT spin densities. The intent is a transferable fragment description that can be embedded in larger polymer oxidation and space-charge modeling workflows without full QM on every timestep.

Methodological motivation is that acetophenone radical anions are resonance-stabilized and can delocalize under standard DFT, so C-DFT center constraints supply diabatic site energies that e-ReaxFF can fit without ambiguous delocalized references.

Methods

The papers/Penrod_Burgess_JCP_Acetophenon_eReaxFF_galley_2021.pdf is an AIP author proof; citable version-of-record text, pagination, and display equations live on 2021penrod-j-chem-phys-using-c-dft (Penrod_Burgess_JCP_Acetophenon_eReaxFF_2021.pdf).

Methods (VOR is authoritative). The AIP version-of-record and 2021penrod-j-chem-phys-using-c-dft give the citable protocol: C-DFT training data, eReaxFF refit on the 2021 Akbarian parent, and NVT eReaxFF molecular dynamics in LAMMPS on periodic acetophenone-centered supercells (time step in fs, temperatures in K, run lengths: Section 2 + SI; Nosé–Hoover-class thermostat on the VOR). This proof path is N/A for line-by-line re-keying; use the VOR + SI for fs/ps settings, NPT (if present in SI), and PBC details. Hydrostatic pressure (bar) — N/A in the NVT demos highlighted in the letter. E-field, umbrella, shock — N/A in the NVT eReaxFF demos as described on the VOR page.

Findings

Practical (corpus). pdf_sha256 on this slug differs from the VOR file; use 2021penrod-j-chem-phys-using-c-dft for hash-locked ingest and bibliography tied to the AIP version-of-record PDF.

Outcomes and comparisons. The VOR reports that C-DFT-aligned eReaxFF reproduces constrained energetics and that NVT eReaxFF trajectories match unconstrained DFT spin-density features at the level discussed in the JCP paper. Lab cable field-cycling is not a benchmark here. Scope: the VOR Discussion keeps claims to the acetophenone radical anion fragment under the stated approximations; for numbers, use the VOR+SI, not this galley for pagination.

Limitations

Scope is acetophenone and its radical anion under the stated DFT approximations; broader cable additives and electrolyte environments are not parameterized here. Proof-PDF may lack final pagination and figure quality versus 2021penrod-j-chem-phys-using-c-dft.

Reader notes (navigation)