Exploring the multiple solutions of the classical density functional theory using metadynamics based method

The density functional theory (DFT) has been applied to describe confined fluids with great success in the literature. However, the usual numerical methods to solve the Euler-Lagrange equations of the grand potential functional are inefficient, finding local minimum and making the convergence very costly for systems with high complexity. Therefore, we present new numerical methods to accelerate the search of equilibrium density distributions of confined fluids, making it possible to find the DFT solutions directly, even when the system is inside the hysteresis region (more than one local minimum) of a sorption isotherm. Here, we use the PC-SAFT-DFT to describe the confinement of simple molecules, molecules with chain effects, and mixtures. We show that the present methodology is convenient to describe the phase diagrams of confined fluids.

Automated summary

New numerical methods are proposed in this study to accelerate the search for equilibrium density distributions of confined fluids using DFT, even in systems within the hysteresis region of a sorption isotherm. The use of PC-SAFT-DFT to describe different types of confined fluids demonstrates the convenience of this methodology in describing phase diagrams of confined fluids.