  As a model system of the adsorption process of anti-corrosion additives on a
metal surface, molecular dynamics simulations of benzotriazole (BTA) molecules
with copper slabs were completed. As a force field, ReaxFF was used to simulate
both adsorption dynamics and the charge transfer on the solid surface. Two
simulations are presented. In order to investigate the physical adsorption on
the surface, the simulation was done for the adsorption process of BTA
molecules on the copper (II) oxide slab. BTA molecules formed on adsorbed layer
in parallel to the surface, and aggregation of the molecules due to the surface
diffusion was found. In order to investigate the selective and chemical
adsorption on the surface, a hybrid slab, which has both a copper (Cu) area and
a copper (I) oxide (Cu2O) area, was used. A selective adsorption phenomenon was
found. The number of BTA molecules adsorbed on the Cu area is 5 times greater
than that on the Cu2O area. Detailed dynamics focused on charge transfer showed
a surface diffusion and enhancement of polarization due to charge transfer from
the metal surface caused the selective adsorption. In a real phenomenon, the
reason why a few anti-corrosion additives are able to protect a metal surface
is postulated to be due to this selective nature of adsorption onto a newly
formed metal surface.
