  Jet energy transported to quark-gluon plasma during jet-medium interaction
excites the QGP medium and creates energetic thermal partons -- recoil
particles or recoils. Modification of the jet structure in heavy ion collisions
is studied using \textsc{martini}, in which recoil simulation is enabled. In
large systems such as central Pb-Pb collisions, the recoil effect is expected
to be critical due to strong jet-medium interaction. We show the results of the
jet mass function and jet shape function are improved when the recoil particles
are included in the reconstructed jets. We conclude that the energy carried by
the recoil particles are regarded as a part of reconstructed jets and are
necessary in studying jet modification in heavy ion collisions.
