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.