Abstract: The title response was studied using the M06 method based on density functional theory and SMD model method combined with self-consistent reaction field theory. The study showed that the zwitterionic chelate S-A_1 formed by alanine（Ala_1）and Mg²⁺ di-coordination with intramolecular single hydrogen bond is the most stable. The neutral ion chelate S-A_2 formed by the double coordination of Ala_ 2 and Mg²⁺ with intramolecular double hydrogen bond is the second stable. The chiral transition of both S-A_1 and S-A_2 has three pathways. Potential energy surface studies showed that the chiral transition dominant pathways activation energies of S-A_1 and S-A_2 are 297.5 kJ·mol^-1and 266. 5 kJ·mol^-1 respectively in gas phase，and are 157. 9 kJ·mol^-1and 165. 7 kJ·mol^-1 respectively with the effect of water molecules（clusters）. Alanine and Mg²⁺ chelates exist mainly in the form of zwitterions in water solvent environment，and the chiral transition dominant pathways activation energies are 157. 5 kJ·mol^-1. The results showed that the alanine and Mg²⁺ chelate can maintain its chiral characteristics well and is easy to be preserved. It can be used as an ideal medicine or nutrition supplement for alanine and magnesium ions.

Key words: font-family:", ">α-alanine（font-family:", ">α-Ala）, magnesium ion（Mg²⁺）, chiral transition, density functional theory, transition state, self-consistent reaction field theory, energy barrier