Nanoscale Structure and Dynamics of Water on Pt and Cu Surfaces from MD Simulations

The
interaction of liquid water with Pt(111) is investigated with
classical molecular dynamics (MD) simulations, where the forces are
determined using the third-generation charge optimized many-body (COMB3)
interatomic potential. In cases of sub-monolayer water coverage, the
parameterized empirical potential predicts experimentally observed
and energetically favorable √37 and √39 reconstructed
water structures with “575757” di-interstitial defects.
At both sub-monolayer and multilayer water coverages, the structure
of the first wetting layer of liquid water on Pt(111) exhibits a characteristic
distribution where the molecules form two distinct buckled layers
as a result of the interplay between water–metal adsorption
and water–water hydrogen bonds. The dynamic spreading rate
of water nanodroplets on large Pt surfaces (>200 nm2) characterized
by molecular kinetic spreading theory is an order of magnitude slower
than the molecular kinetic rate of the same droplet on close-packed
Cu surfaces due to variation in molecular distributions at the water–metal
interface. These nanoscale MD simulation predictions using the COMB3
interatomic potential demonstrate the capability of capturing both
many-body interactions between H2O and Pt or Cu and hydrogen
bonding in liquid water.