First-principles calculation of the structural, electronic, dynamical and thermodynamic properties of γ-LiAlO2

Abstract

The structural, electronic, dynamical and thermodynamic properties of γ-LiAlO2 are investigated using density-functional perturbation theory (DFPT). The calculated structural parameters are found to differ by less than 0.5% from the available experimental data. The electronic band structure and DOS indicate that γ-LiAlO2 is an insulator with a direct gap of 4.85 eV. Using the linear response theory, vibrational properties are calculated. The phonon dispersion curves, the Born effective charges, the optical-mode frequencies at Г point and LO-TO splitting are reported for the first time. The Raman and infrared-active phonon modes are further assigned and discussed briefly. Our results indicate that the Born effective charges are −1.74 for O atom and +2.49 for Al atom, which are lower than the formal charges of Al and O atom, and the two giant LO-TO splitting occur in A2 and E modes. Additionally, the thermodynamic functions such as ΔF, ΔE, CV and S are predicted using the phonon density of states. The results are in good agreement with experimental values and other available theoretical results. It is expected that these results will provide useful guidance to help with structural characterization of LiAlO2.