New variational wave function for liquidHe3

Variational calculations, with a new wave function based on the Feynman-Cohen correlation operator, are carried out for liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ with a Lennard-Jones potential. The wave function contains three-body correlations and momentum-dependent two-body correlations, in addition to the Jastrow correlations commonly used in variational calculations. The Fermi hypernetted-chain summation methods are generalized to calculate energy expectation values wiith this wave function. The calculated equilibrium energy and density are -2.±0.1 °K and $0.28\pm 0.01{\sigma }^{-3\mathrm{}}$, a significant improvement over the -1.25°K and $0.22{\sigma }^{-3\mathrm{}}$ obtained with the Jastrow wave function, and closer to the experimental -2.56°K and $0.28{\sigma }^{-3\mathrm{}}$.