  We use molecular dynamics simulations with machine-learned atomistic force
fields to simulate photoexcitation of BaTiO3 by a femtosecond laser pulse whose
photon energy exceeds the optical gap. We demonstrate selective displacive
excitation of coherent zone-center ferroelectric mode phonons and of the
strongly anharmonic central mode. We show that the direction of P can either be
reversed by a pulse in hundreds of femtoseconds or, on a longer time scale and
when combined with a weak field, switched to any one of its symmetry-equivalent
directions.
