Characterization of the Landau expansion equation for SrTiO3 under pressure

This work focuses on the characterization of the expansion of Landau's main equation for Pm3̄m structures, which are transformed with symmetry subgroups, associated with M+3 and R+4 special points of the Brillouin zone, under hydrostatic pressure. This solution has been adapted to include the general influence of hydrostatic pressure and the evolution of the order parameter. We present a simple scheme in order to search systematically the ground state of all perovskite structures derivable from octahedral rotations under high pressure. We have applied this adaptation to SrTiO3 perovskite. Results of the characterization of Landau′s equation for the cubic-tetragonal phase transition under pressure are discussed here.