The adsorption energy is computed to be 31.3 and 34.8 kcal/mol for glycine and L-alanine, respectively. Two
hydrogen bonded complexes are identified: one is the cyclic double hydrogen bonded complex via the interactions of the carboxyl group
and the zeolite acid site having adsorption energies of 25.4 and 30.0 kcal/mol for glycine and L-alanine, respectively.