THE STRUCTURE OF WATER AT PLATINUM WATER INTERFACES - MOLECULAR-DYNAMICS COMPUTER-SIMULATIONS/

Three pairs of simulations are considered in this work: two simulation s of the water lamina between Pt surfaces at zero external electric fi eld, two simulations with the external field turned on and having a va lue of 10(10) V/m and finally two simulations with the field having th e value of 2 x 10(10) V/m. In every pair of simulations we considered the cases of water lamina embedded between two Pt(100) surfaces and be tween two Pt(111) surfaces. Our simulations demonstrate that water nex t to a Pt surface is profoundly influenced by this surface. When the s urface is uncharged, we observed that the water structure is distorted from its bulk structure to distances of similar to 1 nm from the surf ace. The simulations show that the water layer adsorbed on a surface i s in a solid-like state. The second and the third layer of water are l iquid, but the orientational distribution in these layers show prefere nce towards the orientations that are characteristic for hexagonal ice . When we turn on a homogeneous electric field of value 10(10) V/m wat er molecules reorient, aligning their dipoles along the field. When th e field is doubled compared to the previous value, a dramatic change i s seen in the density profile, indicating that water in the lamina has undergone crystallization.