Elastic Constants and Phonon Dispersion Curves of Tetragonal La₂CuO₄ Single Crystal

The elastic constants and phonon dispersion curves of tetragonal La₂CuO₄ single crystal are calculated with rigid-ion model. We obtain rather good agreement between the computed and measured elastic constants. The calculated phonon dispersion curves exhibit a rather conventional behavior except the anomaly of a Σ₄, symmetry TO mode at Γ-X direction.