Morse potential-based model for contacting composite rough surfaces: Application to self-assembled monolayer junctions

Abstract

This work formulates a rough surface contact model that accounts for adhesion through a Morse potential and plasticity through the Kogut-Etsion finite element-based approximation. Compared to the commonly used Lennard-Jones (LJ) potential, the Morse potential provides a more accurate and generalized description for modeling covalent materials and surface interactions. An extension of this contact model to describe composite layered surfaces is presented and implemented to study a self-assembled monolayer (SAM) grown on a gold substrate placed in contact with a second gold substrate. Based on a comparison with prior experimental measurements of the thermal conductance of this SAM junction [Majumdar et al., Nano Lett. 15, 2985–2991 (2015)], the more general Morse potential-based contact model provides a better prediction of the percentage contact area than an equivalent LJ potential-based model.