Molecular level insights for the corrosion inhibition effectiveness of three amine derivatives on the carbon steel surface in the adverse medium: A combined density functional theory and molecular dynamics simulation study

The adsorption behaviour and mechanism of corrosion inhibition for three amine derivatives, viz., N¹-(2-aminoethyl)ethane-1,2-diamine (DETA), N¹-(2-(2-aminoethylamino)ethyl)ethane-1,2-diamine (TETA) and N¹-(2-(2-(2-(2-aminoethylamino)ethylamino)ethylamino)ethyl)ethane-1,2-diamine (PEHA) on the steel surface have been explored by density functional theory (DFT) and molecular dynamics (MD) simulations. Quantum chemical parameters like E_HOMO, E_LUMO, energy gap (∆E), electron affinity (A), electronegativity (χ), global hardness (η), softness (σ) and the fraction of electron transferred (∆N) from the inhibitor molecule to the metal surface have been calculated and discussed. Fukui indices analysis has also been carried out for investigating the active sites present in these molecules. Additionally, MD simulations have been executed to explore the configurationally adsorption behaviour of these amine derivatives on Fe (1 1 0) surface. The obtained binding energy of these three inhibitors follows the order PEHA > TETA > DETA, is also similar to a trend obtained from experimental analysis.