Quantum chemical studies of some amino acids on the corrosion of cobalt in sulfuric acid solution

The inhibitive effect of some amino acids, glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), serine (Ser), threonine (Thr), methionine (Met), phenylalanine (Phe), tyrosine (Tyr), trytophan (Try), aspartic acid (Asp), asparagine (Asn), glutamic acid (Glu), and lysine (Lys) against the corrosion of cobalt surface is studied by means of semiempirical and density functional methods. The calculated quantum chemical parameters correlated to the inhibition efficiency are, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the energy gap (ΔE), and Mulliken charges. It is found that the calculated results satisfactorily support the experimental findings.