Minkowski functionals for phase behavior under confinement

Abstract: In this work, the Minkowski functionals are used as a framework to study how morphology (i.e. the shape of a structure) and topology (i.e. how different structures are connected) influence wall adsorption and capillary condensation under tight confinement. Numerical simulations based on classical density functional theory (DFT) are run for a wide variety of geometries using both hard-sphere and Lennard-Jones fluids. These DFT computations are compared to results obtained using the Minkowski functionals. It is found that the Minkowski functionals can provide a good description of the behavior of Lennard-Jones fluids down to small system sizes. In addition, through decomposition of the free energy, the Minkowski functionals provide a good framework to better understand what are the dominant contributions to the physics of a system. Lastly, while studying the phase envelope shift as a function of the Minkowski functionals it is found that topology has a different effect depending on whether the phase transition under consideration is a first- or a second-order transition.