Molecular hydrodynamic approach to dynamical correlations in quantum liquids.

A quantum molecular hydrodynamic formalism is developed for the study of dynamics in quantum liquids. The method combines exact static input, generated by path-integral Monte Carlo, and an approximate form of the quantum memory function for the solution of the exact quantum generalized Langevin equation under consideration. This methodology is applied to the study of the spectrum of density fluctuations in liquid para-H2. Using a physically motivated approximation for the memory function, semiquantitative agreement is obtained for S(k,omega) in comparison to the recent experiments of Bermejo et al. [Phys. Rev. Lett. 84, 5359 (2000)]. Improvement of the methodology and future applications are discussed.