Phonon dynamics of lanthanum manganite LaMnO3 using an interatomic shell model potential

We have investigated the detailed phonon dynamics of the magnetoresistant lanthanum manganite (LaMnO3) using a shell model with pairwise interionic interaction potential. The investigations include the computation of the phonon density of states, the specific heat, the elastic constants, and the phonon-dispersion curves of LaMnO3. The symmetry vectors obtained through detailed group-theoretical analysis at the zone center point were employed to classify the phonon frequencies obtained into their irreducible representations. This analysis enabled direct comparison with the observed Raman and infrared spectra. Furthermore, we have computed the specific heat at constant volume at different temperatures and the phonon-dispersion curves along the three major symmetry directions for LaMnO3. The results have been found to present an overall better interpretation of the available experimental data as compared to those obtained from other theoretical model calculations.