  The dynamics of the one-tangle and the concurrence is analyzed in the
Lipkin-Meshkov-Glick model which describes many physical systems such as the
two-mode Bose-Einstein condensates. We consider two different initial states
which are physically relevant and show that their entanglement dynamics are
very different. A semiclassical analysis is used to compute the one-tangle
which measures the entanglement of one spin with all the others, whereas the
frozen-spin approximation allows us to compute the concurrence using its
mapping onto the spin squeezing parameter.
