  The behavior of the local mode potential energy in the unit cell of BaTiO3 is
studied by effective Hamiltonian numerical simulations. The study is focused on
the evolution of the potential minimum felt by the Ti ion. At the paraelectric
phase, the single instantaneous minimum is located at one of eight off-centered
regions at the body diagonals of the unit cell. The study shows graphically how
the soft mode behavior of the perovskite comes from the average response of the
Ti ion to the potential changes in the unit cell, showing that the single
minimum of the time-averaged potential is centered at the paraelectric phase
and off-centered at the ferroelectric phase.
