Abstract: Quantum chemical density functional theory was used to study the interaction between the polar groups of friction modifiers (polyols, amide, carboxylic acid, amine, alcohol, and methyl ester) and metal iron. The structural characteristics of modifiers were studied to judge the active atoms of the modifiers and the possibility of chemisorption. The results show that the chemical action occurs between Fe and organic friction modifiers, such as propionic acid, propionate, propionate, propionate, propylamine. While physical action happens between propanol and Fe. The chemical adsorption energies were calculated between 5 kinds of polar groups and Fe. The intensity of adsorption is in the order: propionic acid glyceride ≈propylamine > propionic acid amide > propionic acid ≈methyl propanoate > propyl alcohol.

Key words: quantum mechanics, friction modifier, chemisorption, physical absorption