The adsorption phenomenon
of refrigerant R-1233zd(E) molecules
on a hematite Fe2O3(011̅2) 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
(P
z
= 500 MPa) and shearing
(v
s = 20 m/s).
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