Computational simulation of the molecular structure of some triazoles as inhibitors for the corrosion of metal surface

The density functional theory (DFT) at the B3LYP/6-31G++ (d p) basis set level, ab initio calculations using the HF/6-31G++ (d p) and semi-empirical PM3 methods were performed on four triazole derivatives used as corrosion inhibitors, namely (5-amino 1,2,4 triazole (5-ATA), 5-amino-3-mercapto 1,2,4 triazole (5-AMT), 5-amino-3-methyl thio 1,2,4 triazole (5-AMeTT), 1-amino-3-methyl thio 1,2,4 triazole (1-AMeTT)), to investigate the correlation between its molecular structure and the corresponding inhibition efficiency (%IE). Quantum chemical parameters such as the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (μ), sum of total negative charges (TNC), molar volume (MV), electronegativity (χ), hardness (η), softness (σ) and the fraction of electrons transferred from the inhibitor molecule to the metal surface (ΔN), have been calculated. Furthermore, the adsorption energies of the inhibitors with the copper (1 1 0) surface were studied using molecular dynamic (MD) method. A good correlation between the theoretical data and the experimental results was found.