Conclusion
The present study was carried out using multipple theoretical approaches (DFT, MC, MD, RDF). which allows a relatively good reproduction of experimental corrosion results (EIS,Tafel). Similar order of protection efficiencies (PPD>OPD) obtained experimentally was complemented with the parameters of DFT global descriptors, MC, MD and RDF analysis. Computed global descriptors like higher chemical softness (0.736), polarizability (650.707 a.u) and small energy gap (−2.202) obtained for PPD molecule; emphasize its corrosion suppressing characteristics. Fukui indices and Mulliken atomic charges depicted the adsorption centers of the PPD and OPD additives. Higher binding energy (Ebinding=1132.241 kJ/mol) and larger negative interaction energy (Einteraction= −1132.241 kcal/mol) and greater flat-lying adsorption orientation of PPD molecule affirms the reduction in diffusion of corrosive species. Stronger interactive forces i.e chemisorption between Ni-W alloy and additive molecules was revealed through RDF analysis. Larger negative value of adsorption energy (Eadsorption= −195.55 kcal/mol) from monte carlos, authenticates its spontaneity, stability and higher surface coverage area; fabricating an packed additive film. Finally, a fruitful insight, providing a pellucid picture of interfacial interactions occurring between Ni-W alloy and additive molecules (OPD & PPD) was deduced in correlation with the previously reported experimental results.