AZIZ FERMIONS AND LIQUID-HE-3

Starting from the well-known quantum-field-theory low-density expansion for the ground-state energy of a strongly interacting many-fermion assembly, we rearrange the series into a quantum-thermodynamic perturbation theory that is then applied to liquid He-3. Extrapolation to physical densities is implemented order by order via Pade and related approximants. We employ both the hard-core square-well potential and the Aziz pair potential with the Barker-Henderson (BH) and Weeks-Chandler-Andersen (WCA) potential-decomposition schemes familiar from classical fluid studies. The binding energy, saturation density, and sound velocity are calculated, with no adjust-able parameters, and compared with Green-function Monte Carlo (GFMC) computer simulations, experimental data, and recent variational calculations. Our binding-energy and saturation-density results for the Aziz-WCA case, and the sound velocity result for the Aziz-BH case, are found to be within 2% of the GFMC data.