  The properties of the ground state of liquid $^4$He are studied using a
correlated basis function of the form $\prod_{i<j} \psi(r_{ij})$. Here,
$\psi(r)$ is chosen as the exact solution of the Schr\"{o}dinger equation for
two $^4$He atoms. A hard-sphere plus an attractive square well is used as the
interaction potential between $^4$He atoms. The pair distribution function is
calculated using approximate integral methods, namely the Percus-Yevick (PY)
equation and Hypernetted Chain (HNC) approximation. The values thus obtained
are used to calculate the ground state energy, which is found to be -4.886 K
using the PY equation. The liquid structure factor is also obtained using the
pair distribution function. The values for the pair distribution function and
liquid structure factor are compared with experimental results and earlier
theoretical calculations.
