Ground state of liquid⁴He

A variational calculation of the ground-state energy of liquid4He is performed under the assumption that the ground-state wave function is a product of pair functions and the potential energy is a sum of pair potentials. Results obtained from the Percus-Yevick (PY) and Hypernetted Chain (HNC) theories are compared with both Monte Carlo (MC) studies and with experiment. It is found that in the case studied the PY equation is considerably less accurate than the HNC and that the PY is not useful for this variational calculation but that the HNC is. A comparison of three model pair potentials indicates that the uncertainty in the pair potential produces an uncertainty in the ground-state energy of about 2°K. One of the pair potentials used leads to the best agreement yet obtained with experimental ground-state energies. © 1970 Plenum Publishing Corporation.