First-principles investigations of structure and vibrations of c(4x2) PF₃ on Cu(001)

We use first-principles density functional theory(DFT) to study the structure and vibrational dynamics of PF₃ on the Cu(001) surface in the c(4x2) geometry. This system presents a unique opportunity to consider the complex interplay at work when a molecule with 3-fold symmetry binds to a surface with 4-fold symmetry. Our calculations find an upright structure for the PF₃ molecules, in contrast to experimental claims. The phonon analysis reveals an intersting coupling between adsorbate modes, surface mods and bulk modes. We will present detailed calculational evidence, including phonon density of states and projected density of states to support the rich structural and vibrational behavior that this system affords.