  We investigate entanglement in a linear chain of $N$ polar molecules coupled
by dipole interaction. In our model, nearest neighbour interaction predominate,
and we compute entanglement with the help of a two-party correlation
entanglement measure. We find that, in this system, only excited states are
entangled. Moreover, when an electrostatic field is applied, energy levels
crossings occur, changing significantly the system's entanglement properties.
We make a systematic study of the entanglement dependency on the inter
molecular distance separating pairs of molecules, different partitions of the
chain and physical parameters as the temperature and the electrostatic field's
intensity, showing that it persists for relatively high temperatures and
changes its nature with varying field.
