(482c) Interface Force-Field (IFF) Parameterization of Ti3C2TX Mxenes

Since their discovery in 2011 by Gogotsi et al., two-dimensional (2D) MXene materials have attracted growing interest due to their multi-functional properties, such as high electric conductivity (for superior electromagnetic interference (EMI) shielding properties), and high in-plane mechanical strength (filler reinforcements for structural applications), among others. Given their inherent 2D nature, these materials possess low shear resistance in their pristine form, limiting their applicability in applications which require structural stability under working conditions. In this context, accurate modeling of shear behavior at nanoscale would illuminate desired surface features that can maximize their shear strength. This limitation necessitates development of a MXene force-field which can accurately model inter-flake interactions via atomistic molecular dynamics simulations, to provide insights on modulating shear and related surface characteristics of MXenes. In this work, we develop accurate and compatible force-field parameters for Ti3C2Tx, one of the most studied MXenes, with hydroxyl (-OH) and fluoride (-F) terminated surface functional groups as a part of the Interface Force Field (IFF). The IFF incorporates atomic charges and non-reactive chemical bonding as well as non-bonded van der Waals and electrostatic interactions. The model is validated against experimental reference data including lattice parameters obtained via X-Ray scattering, surface energies, contact angles, and in-plane/out-of-plane mechanical properties. Furthermore, a genetic-algorithm (GA) based machine learning framework interfaced with LAMMPS has been employed to refine and optimize the force-field parameters. The developed IFF model for MXenes can be used to simulate interfaces with organic and biological molecules, solvents, and inorganic materials without additional parameters. The model setup and parameters outlined in this work are easily extendable to other types of MXene materials.