We have measured the intermolecular structure factor and its thermodyn
amic derivatives in the vicinity of the triple point of liquid deuteri
um, using two different neutron sources. We have also derived the same
quantities by using path integral Monte Carlo computer simulations. F
or the structure factor, we find good agreement between the experiment
s and the simulation results, using either the Lennard-Jones or a more
realistic phenomenological potential. However, when the comparison is
extended to the thermodynamic derivatives, a clear difference is obse
rved between the two different intermolecular potentials.