Jastrow wave function and correlations of the Lennard-Jones Bose fluid

We present results of Monte Carlo variational calculations for the ground state of the Lennard-Jones fluid. The Jastrow pseudopotential contains a correlation structure, that has been suggested to manifest the zero-point motion of rotons, at a distance of the order of first and second shell of neighbors. We find an improved ground-state energy, and its density dependence is in fair agreement with the "exact" result. The variational $g\left(r\right)\mathrm{}$ and $S\left(k\right)\mathrm{}$ are now in excellent agreement with the "exact" result. A comparison is made with the functional minimization approach. Computation of $S\left(k\right)\mathrm{}$ at finite temperature is performed with Penrose's density matrix by the Monte Carlo method and by application of perturbation theory of classical liquids.