Phonon band structure and electron-phonon interactions in metallic nanowires

We present first-principles calculations of the phonon band structure and electron-phonon coupling in thin metallic nanowires. A full Brillouin zone analysis of the phonons is mandatory for the investigation of the nanowire structural stability: all the examined unstrained nanowires show instabilities whose wave vectors are located off the zone center. The unstable phonon modes are transverse, leading to a transition without a gap opening, in contrast with the usual Peierls distortion picture. Electron-phonon coupling yields orders-of-magnitude changes depending on the nanowire structure.