Computational Modelling of MOF Mechanics: From Elastic Behaviour to Phase Transformations

This chapter critically reviews the computational tools for the in silico modelling of MOF mechanics from the atomic level onwards. To this end, the macroscopic properties describing the mechanical behaviour of these materials – such as stress and strain – are formulated in terms of atomistic information that can be readily extracted from quantum mechanical or classical computer simulations. This immediately reveals the fundamental challenges that arise when attempting to computationally predict the wide array of responses which MOFs exhibit under mechanical stimuli. The different techniques to extract the mechanical behaviour of MOFs near equilibrium – especially the elastic constants – are contrasted with one another through representative literature examples. While these elastic constants capture the response of a material to small mechanical stimuli, different approaches are required to computationally predict how MOFs respond to larger stresses. A distinction is made between those techniques suitable to describe single-crystal-to-single-crystal phase transitions on the one hand, and those applicable to describe single-crystal-to-amorphous phase transitions, a field that currently remains in its infancy, on the other hand. Through various illustrations from literature, this chapter highlights the open questions arising in each of these topics and explores how ongoing research aims to tackle these challenges.