We present a first-principles linear-response study of the phonon spectrum and dipole activity of the Si(111)2 x 1 surface. Our results are in good agreement with the experimental He-scattering results for the acoustic modes, as well as the electron-energy-loss data for the optical modes. We clarify a current controversy on the assignment of the electron-energy-loss peak at approximately 56 meV. We find that the dominant contribution to the loss peak is anisotropic and arises from a longitudinal-optical vibration of the surface chains. However, a small but non-negligible isotropic contribution comes from subsurface modes polarized perpendicular to the surface.
|Titolo:||Surface phonons and dipole activity of Si(111)2×1 from ab initio calculations|
|Autori:||Ancilotto, F; Selloni, A; Andreoni, W; Baroni, Stefano; Car, R; Parrinello, M.|
|Data di pubblicazione:||1991|
|Digital Object Identifier (DOI):||10.1103/PhysRevB.43.8930|
|Appare nelle tipologie:||1.1 Journal article|