Quantum Mechanics/Molecular Mechanics (QM/MM) applied to tribology: Real-time monitoring of tribochemical reactions of water at graphene edges

Tribological phenomena, such as wear and boundary lubrication, are deeply influenced by tribochemical re- actions, i.e., chemical reactions occurring in the presence of mechanical stresses. Atomistic descriptions of these processes are still in their infancies because of the high computational costs required to properly describe the buried sliding interface by theoretical methods. In this paper we outline the application of the Quantum Mechanics/Molecular Mechanics approach to simulate tribochemical reactions during sliding and show that it can accurately describe the tribochemistry of graphene interacting with water molecules, a system which is of relevance for technological applications. Comparison with ab initio (Car-Parrinello) and classical (using the ReaxFF force field) molecular dynamics calculations highlights the advantages of this hybrid approach both in terms of computational costs and accuracy of the results.