Energy of a Boson Fluid with Lennard-Jones Potentials

A more powerful version of a numerical method published before is given which permits the integration of the Schrödinger equation for a large ensemble of particles. A new method for obtaining quantum expectation values is outlined. Numerical results are tabulated for the energy of the ground state of a system of 32 bosons interacting by Lennard-Jones potentials and with periodic boundary conditions. This is a commonly used model of liquid ${\mathrm{He}}^4$. The present results are substantially lower and closer to experiment than variational estimates based on a Jastrow-type wave function.