On the modeling of hydrocarbon combustion in external electric fields with reactive molecular dynamics.

This article focuses on evaluating methodologies for simulating hydrocarbon fuel combustion in external electric fields using reactive molecular dynamics (MD) with the reactive force field ReaxFF. It compares two atomic charge computation methods: the charge equilibration method (QEq), which allows unphysical long-range charge transfer leading to molecules with sizable net charges, and the charge transfer with polarization current equilibration method (QTPIE), which reduces such artifacts but tends to underestimate some atomic charges. The study proposes a two-step equilibration procedure to better prepare fuel–oxygen systems at target temperatures and analyzes the impact of global thermostats, such as Nosé–Hoover and canonical sampling through velocity rescaling, on reaction kinetics under electric fields. It finds that global thermostats artificially redistribute kinetic energy—reducing vibrational energy critical for reactions—thereby slowing combustion rates, an artifact avoided by using microcanonical (NVE) simulations that, however, allow continuous heating due to the electric field. The work highlights the need for improved charge computation methods and temperature control strategies to accurately model combustion chemistry in electric fields without introducing simulation artifacts.