The AMOEBA force field is distributed with the Tinker software package . To determine the IR spectrum, the electric dipole moments were collected for multiple trajectories, then processed through the Fourier transform of the time autocorrelation function of the electric dipole moments by the ChirPy program . This gave an individual spectrum for each trajectory from which an average spectrum was determined. In the gas phase, 40 trajectories were performed and in the condensed phases 30 trajectories were assembled. A time step of 0.5 fs was employed as it is found to be optimal for IR spectroscopy in this frequency range , and the electric dipole moments were collected with a time step of 4 fs for the Fourier transform of the autocorrelation function. All systems were pre-equilibrated at 300 K with the Nosé-Hoover thermostat before the electric dipole moments were recorded.