  The study combines DFT calculations and CPMD simulations to investigate the
structures of phenylalanine-copper (II) ([Phe-Cu]2+) complexes and the
micro-solvation processes. ....It is found that the phenylalanine moiety
appears to be in the neutral form in isolated and mono-hydrated complexes, but
in the zwitterionic form in other hydrated complexes (with n no less than 2).
.... The present CPMD simulations reveal that the maximum coordination of Cu2+
in the presence of the Phe ligand does not exceed four: the oxygen atoms from
three water molecules and one carboxyl oxygen atom of Phe. Any excess water
molecules will migrate to the second solvation shell. Moreover a unique
structural motif is present in the lowest energy complexes, which is recognized
to be significant in stabilizing the structures of the complexes. .....
