Background Polarization Corrections to the Davydov Splittings of Phosphate Vibrations

The effects of the host dielectric properties on the magnitudes of the Davydov splittings and infrared oscillator strengths of the phosphate T2 vibrations in Ca10(PO4)6F2 have been calculated. The splittings and oscillator strengths are shown to depend on the magnitude of the background polarizability, which is the polarizability due to the electronic transitions and the other vibrations of the host as evaluated at each T2 frequency. The dependence of each vibrational frequency on the host dielectric properties is a function of the symmetry of the vibrational mode. The numerical values of the frequencies of the Raman-active and infrared-active modes, including the dependence of the latter on propagation direction, computed using the experimental oscillator strengths and polarizabilities, agree well with the experimentally determined frequencies.