The optical phonon spectrum of SmFeAsO

¹  CNR-INFM “Coherentia” and Dipartimento di Fisica, Università di Roma “La Sapienza” P.le A.Moro 2, 00185 Roma, Italy, EU
²  “Unitá CNISM Roma1” - Dipartimento di Fisica “E. Amaldi”, Università degli Studi Roma Tre Via della Vasca Navale 84, 00146 Roma, Italy, EU
³  CNISM - Dipartimento di Fisica, Università degli Studi dell'Aquila - Via Vetoio 10, I-67010 Coppito (AQ), Italy, EU
⁴  Sincrotrone Trieste S.C.p.A. - S.S. 14 km 163.5, in Area Science Park, 34012 Basovizza (TS), Italy, EU
⁵  SLACS-INFM/CNR and Dipartimento di Scienze Fisiche, Università degli Studi di Cagliari I-09042 Monserrato (CA), Italy, EU
⁶  CNR-INFM-LAMIA and Dipartimento di Fisica - Via Dodecaneso 33, 16146 Genova, Italy, EU
⁷  CNR-INFM-LAMIA and Dipartimento di Chimica e Chimica Industriale - Via Dodecaneso 31, 16146 Genova, Italy, EU

Corresponding author: paolo.dore@roma1.infn.it

Received: 13 October 2008
Accepted: 21 November 2008

Abstract

We measured the Raman and the infrared phonon spectrum of SmFeAsO polycrystalline samples. We also performed density functional theory calculations within the pseudopotential approximation to obtain the structural and dynamical lattice properties of both the SmFeAsO and the prototype LaFeAsO compounds. The measured Raman and infrared phonon frequencies are well predicted by the optical phonon frequencies computed at the point, showing the capability of the employed ab initio methods to describe the dynamical properties of these materials. The present study and the comparison among the phonon frequencies of different oxypnictides can provide a theoretical/experimental background for stimulating further investigations on the role of phonons in the physics of these materials.