Dielectric properties and long-wavelength optical modes of the high-kappa oxide LaAlO3

We present ab initio density-functional and self-interaction-corrected calculations on the structure, long-wavelength vibrational modes, and static dielectric properties of the crystalline high-kappa distorted-perovskite oxide LaAlO3. The orientationally averaged dielectric constant kappa similar or equal to 23.3 is in good agreement with experiment, and its value is dominated by the ionic response. We find it important to calculate the dynamical charges by a self-interaction-corrected scheme, bringing about a similar to 15% improvement on the DFT result. We report on the infrared- and Raman-active vibrational modes, which are in good agreement with experiment where applicable, and we discuss the origin of the recently observed dielectric anisotropy.