The second-order Raman spectra of diamond and silicon have been calculated using ab initio phonons and phenomenological polarizability coefficients. The sharp peak in the spectrum of diamond near the two-phonon cutoff is explained by a maximum in the vibrational density of states; this maximum originates from the uppermost phonon branch whose frequencies are calculated to have a minimum at the Brillouin-zone center. This frequency minimum as well as the sharp Raman peak are unique to diamond and do not occur for the other group-IV semiconductors. In our calculation based on harmonic ab initio lattice dynamics neither two-phonon bound states nor polarizability matrix element effects are needed to explain the peak, and we feel that the longstanding controversy about its origin has been resolved.
|Titolo:||Second-order Raman spectra of diamond from ab initio phonon calculations|
|Autori:||Windl, W.; Pavone, P.; Karch, K.; Schütt, O.; Strauch, D.; Giannozzi, P.; Baroni, S.|
|Data di pubblicazione:||1993|
|Digital Object Identifier (DOI):||10.1103/PhysRevB.48.3164|
|Appare nelle tipologie:||1.1 Journal article|