Figure 1. In the surface NEGF methodology, surface is represented as a truly semi-infinite system, which is divided into a finite surface region and a semi-infinite bulk region. One can also apply either a positive or negative external electric field. A Dirichlet boundary condition is used at the boundary between the bulk electrode region and the surface region, whereas in the vacuum region, a Neumann (Dirichlet) boundary condition is used for surface calculations without (with) an electric field.
Figure 2. Relative stabilities of I2V and I2P configurations under negative and positive electric fields. I2V configuration is preferred in a reductive environment for IRR dictated by a negative electric field.
Figure 3. Consecutive mechanism for the I2V reduction reaction on the Pt(111) surface. The reaction is initiated by I2V approaching the Pt(111) surface and then I atoms are sequentially reduced due to asymmetric charge accumulation on a single I atom that is subsequently desorbed in the reductive environment dictated by a negative electric field.
Figure 4. Interatomic distance of I2V molecule (dI(2)-I(1)) (a) and adsorption distance of I(1)* on the Pt(111) surface (dPt(111)-I(1)*) (b) as a function of the electric field. The slopes of the linear relation (0.45 and 0.36) in this plot represent the ability of the partial reduction of the adsorbent.