Investigation of the effect on the adsorption behavior of poly(aspartic acid) and poly(glutamic acid)on Fe (110) surface by DFT and MD

One of the major characteristics of high-molecular-weight polymerization is its poor water solubility. Because of the significant impact this situation has on the usage of corrosion inhibitors, it is imperative to research low-molecular-level green amino acid corrosion inhibitors, particularly at the molecular level. Therefore, in this paper, we studied the effect of density functional theory (DFT) and molecular dynamics (MD) on the adsorption performance of aspartic acid (Asp) and glutamic acid (Glu) on the iron surface. We theoretically evaluated the adsorption energy by analyzing the formation of chemisorption of amino acid molecules with different polymerization degrees through electron transfer. The results showed that the optimum degree of polymerization was 8 for Asp that of Glu was 6, because the peptide bond and carboxylic acid root were attached to the d orbital of the iron atom. The adsorption energies at the optimum degree of polymerization were -304.457939 kcal/mol and -286.312175 kcal/mol for Asp and Glu, respectively, which demonstrated that Asp is a better corrosion inhibitor than Glu. This paper provides a theoretical approach for the design of subsequent corrosion inhibitors and the selection of polymerization degree.