Shenzhen Jingtai Technology Co. 1 article published in JoVE Chemistry Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method Zhihui Tu1,2, Jian Yin3, Liangxu Xie4 1State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 2University of Chinese Academy of Sciences, 3XtalPi Inc. (Shenzhen Jingtai Technology Co., Ltd.), 4Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology A protocol that uses enhanced QM/MM method to investigate the isotopic effect on the double proton transfer process in porphycene is presented here.