Chemical Physics at Interfaces within a Refrigerant-Lubricated Contact: From Electronic Structure to Large-Scale Molecular Dynamics Simulations

Abstract

The adsorption phenomenon of refrigerant R-1233zd(E) molecules on a hematite Fe2O3(0112) surface is studied at the quantum level thanks to density functional theory + U (DFT + U) calculations employing a van der Waals functional combined with a spin-polarized system. The results show different adsorption sites on the solid surface depending on orientations of the molecule, characterizing strong interactions between the refrigerant molecule and both iron and oxygen atoms. A range of binding energy values of −0.92 to −0.22 eV is observed. These ab initio results are used to parametrize a force field at the refrigerant–hematite interface for larger scale molecular dynamics simulations. Effects of these ab initio considerations on density and velocity profiles are studied, in the case of a confined fluid between two surfaces as in a lubricated contact. The high binding energy values induce a locking effect of the R-1233zd(E) molecules close to the hematite surface, showing a resistance to compression (Pz = 5...