  We have used ab-initio density functional theory technique to understand the
phase transitions and structural changes in various high temperature/pressure
phases of LiAlO2. The electronic band structure as well as phonon spectra are
calculated for various phases as a function of pressure. The phonon entropy
used for the calculations of Gibbs free energy is found to play an important
role in the phase stability and phase transitions among various phases. A
sudden increase in the polyhedral bond lengths (Li/Al-O) signifies the change
from the tetrahedral to octahedral geometry at high-pressure phase transitions.
The activation energy barrier for the high-pressure phase transitions is
calculated. The phonon modes responsible for the phase transition (upon
heating) from high pressure phases to ambient pressure phases are identified.
Moreover, ab-initio lattice dynamics calculations in the framework of
quasi-harmonic approximations are used to calculate the anisotropic thermal
expansion behavior of {\gamma}-LiAlO2.
