Passivation is the process by which the iron surface becomes less reactive by forming a protective oxide layer that prevents further corrosion. DorMohammadi et al. examined the early stages of the iron corrosion process in water using reactive molecular dynamics. As shown in Figure (a), a system of the Fe(110) slab with 2016 iron atoms and 480 water molecules was formed to simulate a water environment with a density of 0.99 g cm -3 . The simulation was carried out for 150 ps with 0.1 fs time step using NVT ensemble. This study proposed four different stages of the corrosion process based on simulation results. Initially, water molecules started to be adsorbed on the surface and dissociated into surface-bound hydroxyl groups while releasing hydrogen (H + ) back into the solution to form H3O + . Then, some of the surface-bound hydroxyl groups dissolve into the solution to form iron hydroxides (FeOH). Next, these iron hydroxides reacted with acidic H3O + to form water and iron ion complexes. Finally, dissolved iron ions formed the corrosion products. The thickness of the oxide layer increased with time due to the continuous formation of iron oxides and hydroxides from the dissolved irons. valence iron oxides whilst zero valent region can be attributed to the region where oxides did not penetrate. Such a versatile charge distribution for the same species, along with analysis of pair distribution functions, demonstrated the generation of different phases of oxides including hematite (Fe2O3), wustite (FeO), and magnetite (Fe3O4). Passive film formation in a highly alkaline environment was investigated. DorMohammadi et al. carried out simulations on the Fe(110) surface exposed to a 13.5 pH NaOH solution using an NVT ensemble at 300 K. The electrolyte was composed of 348 water molecules and evenly distributed 21 Na + and OH -ions. Additionally, an external electric field was applied to accelerate the passivation. During the simulation, four key elementary steps were involved: the formation of adsorbed FeOH (eq 12) and Fe(OH)₂ (eq 13) species, the One of the main differences observed in the high alkaline mechanism is the formation of surface Fe(OH)2 components due to excess OH -concentration, which limits the excessive iron dissolving into the electrolyte compared to the neutral medium. In the meantime, oxygen penetrates subsurface layers and oxidizes the iron atoms to form the passive layer, with a rate slowing down to approximately 10% after 500 ps, indicating the formation of a stable passive layer under the conditions used. The pair distribution function of Fe-O of six oxide layers is shown in Figure . The composition of these layers demonstrates the formation of Fe2O3 in the outer two layers, and each middle and inner two layers are composed of Fe3O4 and FeO respectively. While the charge distribution map (Figure ) directly supports the observations from the pair distribution function, significant differences were observed when compared to the formation of oxides in neutral pH (Figure ). For instance, the charge of the iron atoms gradually decreased from the inner passive layer to the outer passive layer in an alkaline medium supporting the formation of stable passive film. On the contrary, distinct regions of iron charges were observed in the neutral pH simulation, with some iron atoms near the interface showing very high positive charges. The studies provide the essential information in the initial stage of passive film formation on iron surfaces in neutral and alkaline environments. electric field of 25 meV cm -1 at a neutral pH level. Reprinted with permission from Elsevier. (d) The Fe-O pair distribution function for six consecutive iron oxide layers starting from the passive layer/solution interface at 500 ps in a highly alkaline solution. The first layer being the outermost passive layer. The dotted lines are indicative of reference metal oxides. (e) Charge distribution of main species in the highly alkaline environment at 500 ps. Reprinted with permission from Elsevier.