Abstract: Using the method of density functional theory B3LYP, we investigated the chiral transition process of the phenylalanine molecule under the cooperative action of dualH₂O at the level of 6-311+G(2-df-). We drew a complete reaction potential energy surface for chiral transition path of phenylalanine molecule by finding the structures of the extreme value points including the transition states and intermediates, and analyzed the geometric and electronic structure properties of extreme value points. The results show that the H atom on the chiral C atom of Sphenylalanine molecule can transfer to the other side of the C atom via the O atoms of carboxyl atoms as a bridge, and achieve the chiral transition of phenylalanine molecule from Stype to Rtype. On this path there are four intermediates and five transition states. The maximum reaction energy barrier is 173.808 1 kJ/mol, which comes from the second transition state TS₂SPhe&2H₂O₂.

Key words: phenylalanine, chirality, transition state, dualH₂O