Dielectric properties and long-wavelength optical modes of the high-k 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-? distorted-perovskite oxide LaAlO3. The orientationally averaged dielectric constant of 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 ?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.