Modelisation moleculaire et calcul des frequences de vibration du sousreseau perovskite dans Ct(3)NH(3)PbCl(3)

The perovskite CH(3)NH(3)PbCl(3) presents two low-temperature phase transitions IIIP222(1) 172 K II P4/mmm 179 K IPm3m Orthorombic Tetragonal Cubic The various phases are characterized by Raman scattering. We restrict ourselves to the lowfrequency domain (10-250 cm^-1), which includes the lattice vibrations, these being more sensitive to the symmetry variations and to the structural phase transitions. Studying the crystal dynamics and the spectral evolution requires a detailed assigment of the Raman spectrum. Consequently, we bring in a molecular model and carry out a theoretical calculation of the