  We examine the dynamics after a sudden quench in the magnetic field of the
Lipkin-Meshkov-Glick model. Starting from the groundstate and by employing the
time-dependent fidelity, we see manifestly different dynamics are present if
the system is quenched through the critical point. Furthermore, we show that
the average work shows no sensitivity to the quantum phase transition, however
the free energy and irreversible work show markedly different rates of change
in each phase. Finally, we assess the spectral function showing the fundamental
excitations that dictate the dynamics of the post-quenched system, further
highlighting the qualitative differences between the dynamics in the two
phases.
