Quantum statistics and the momentum distribution of liquid parahydrogen

Extensive Monte Carlo simulations of bulk liquid parahydrogen at a temperature T=16.5 K have been carried out using the continuous-space Worm Algorithm. Results for the momentum distribution, as well as for the kinetic energy per particle and the pair-correlation function are reported. The static equilibrium thermodynamic properties of this system can be generally computed by assuming that molecules are distinguishable. However, the one-body density matrix (and the associated momentum distribution) is affected by particle indistinguishability and quantum statistics to an extent that lends itself to experimental observation. Comparisons with available experimental data and other theoretical and numerical calculations are offered.