Theoretical study of C2H2 adsorbed on low-index Cu surfaces

Ab initio density functional theory was used to determine the adsorption systems Of C2H2 on Cu (100), (111), and (110) surfaces. Infinitely large models with three-dimensional periodic boundary conditions are implemented in these adsorption systems. The results show that the Cu(100) surface was modified from ''square'' to ''rhombus'' through the charge redistribution caused by adsorbing the C2H2 molecules. This reveals that the interaction energy dominates the adsorption system rather than the adsorption energy, which involves large deformation. The interaction energy values of C2H2/Cu systems on different surfaces have a sequence of C2H2/Cu(110) < C2H2/Cu(100) < C2H2/Cu(111). The tilting angle of the H atom is proportional to chemical binding of the systems.