Vibrational spectra of ammonia, benzene, and benzene adsorbed on Si (001) by first principles calculations with periodic boundary conditions -: art. no. 155413

We develop an efficient method for the calculation of dynamical dipoles and frequencies of vibrational transitions in the framework of density-functional theory with periodic boundary conditions. It augments previous approaches by accounting for the substrate influence on the vibrations of the adsorbate. It allows one to reproduce and predict optical infrared and electron energy loss spectra including the correct relative oscillator strengths while still staying in the familiar picture of normal modes so that an intuitive physical interpretation of experimental results is possible.