field was used . AMOEBA was originally developed for biomolecules such as proteins and DNA, and some organic molecules . The main interest of this force field lies in its ability to reproduce relative conformational energies. Conventional force fields that do not include polarization effects only reproduce about 50% of the conformations found at the MP2/aug-cc-pVTZ level of theory whereas AMOEBA reproduces about 80% of them . The good reproduction of the relative energy is due to the use of permanent electrostatic multipolar moments (charges, dipole and quadrupole moments) on each atom, and induced dipoles reacting self-consistently to the presence of local electric fields on each polarizable site. This leads to a good precision for thermodynamic properties such as free energies of solvation and complexation. The AMOEBA force field has also been extended to IR spectroscopy of peptides in the gas phase and hydrated ions very satisfactorily .