Fig. 3

Graphical representation of HOMO, LUMO and energy gap of Glycine, Glycine (NH₂)-ZnO-H₂O (Model 1), Glycine (COOH)-ZnO-H₂O (Model 2), Glycine (NH₂)-MgO-H₂O (Model 3), Glycine (COOH)-MgO-H₂O (Model 4), Glycine (NH₂)-CaO-H₂O (Model 5), and Glycine (COOH)- CaO-H₂O (Model 6) at B3LYP/6-31G(d, p) level of theory.