Assessment of Approximate Density Functional Methods for the Study of the Interactions of Al(III) with Aromatic Amino Acids.

Four approximate Density Functional Theory methods, the standard hybrid B3LYP functional, the hybrid mPW1PW91 functional designed to account for van der Waals forces, the one-parameter meta hybrid TPSSh functional, the general-purpose meta hybrid MPWB1K functional and one Molecular Orbital Theory method, the standard Moller-Plesset perturbation theory up to second-order MP2, have been assessed for studying the complexation modes of the highly acidic Al(III) cation with the three aromatic amino acids, phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp). Based on their performance toward the prediction of the geometrical structure of a number of lowest energy isomers and their relative binding energies, it is concluded that the B3LYP approximate functional renders the desired accuracy at the minimum computational cost.