A multiscale modelling framework to capture atomically resolved interfacial processes at experimentally relevant timescales
File(s)
Author(s)
Ntioudis, Stavros
Type
Thesis or dissertation
Abstract
Molecular-level simulations are crucial in deepening our understanding of complex systems in the energy sector. Computational techniques such as density functional theory (DFT) and molecular dynamics (MD) help uncover the physical, chemical, electronic, and morphological characteristics of materials interfaces such as the thin films formed from lubricant additives, solid electrolyte interphases (SEIs), energy storage devices, catalysts, and porous media. However, traditional MD simulations are computationally demanding and are limited to timescales of roughly a few microseconds. In this thesis, we introduce a hybrid off-lattice kinetic Monte Carlo/molecular dynamics (kMC/MD) scheme capable of extending simulation timescales beyond the temporal limits of MD. The scheme can describe elementary atomistic processes such as reactions, adsorption/desorption, or diffusion. The introduced kMC/MD model was utilised to investigate the thermal decomposition of tricresyl phosphate (TCP) on iron. Kinetic, chemical, and morphological results generated from the model agree well with previous experimental and MD simulation results. Additional spacer layer imaging method (SLIM) and x-ray photoelectron spectroscopy (XPS) experiments were performed to further validate the thermal decomposition model. It was found that the upper layer of the thin film from TCP was rich in carbon-based and iron oxide compounds with diminished phosphate content. On the other hand, the film growth rates were in good agreement with rates reported in other studies and the hybrid kMC/MD predictions. The model was extended to a general hybrid off-lattice kMC/MD simulator called PAPRECA. PAPRECA is fully parallelised and distributed under an open-source license. The developed software is used for the fine-tuning of the thermal decomposition model and the investigation of the effects of temperature and diffusion hopping distance. Finally, a PAPRECA model for accelerated hybrid kMC/MD simulations on the mechanochemical decomposition of TCP is presented and compared to existing MD studies.
Version
Open Access
Date Issued
2025-06-10
Date Awarded
2025-09-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Dini, Daniele
Ewen, James
Sponsor
Engineering and Physical Sciences Research Council
Shell Global Solutions
Grant Number
EP/V038044/1
Publisher Department
Department of Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)