A polarizable water model for intramolecular and intermolecular vibrational spectroscopies.

We have developed a polarizable water model for classical molecular dynamics simulations of vibrational spectroscopies, which covers from low-frequency intermolecular modes to high-frequency intramolecular vibrational modes. The model utilizes the ab initio derived geometry-dependent multipole moment surfaces to depict the instantaneous charge density of a water molecule. Multipoles up to quadrupole are included for the permanent multipoles, while those up to dipole are included for the induced multipoles. The polarization of molecules is described by a distributed polarizability model. At room temperature, the present model is able to reproduce experimental infrared and Raman spectra of intramolecular vibrational modes, except for the blue peak shift due to a limitation of the classical simulation based on a quantum mechanical potential. The calculated infrared spectrum for low-frequency intermolecular modes agreed reasonably well with the experimental signals.