  We point out that a typical two-electron distribution function in atoms and
molecules often called the intracule depends sensitively on the
electron-electron repulsion which leads to the so-called Coulomb correlation.
The difference between the intracule densities computed by using the correlated
and uncorrelated wave functions has been given the name Coulomb hole. Studies
in intracule densities and Coulomb holes form a subject of considerable current
interest. We make use of a three-parameter correlated wave function and its
uncorrelated limit to study the properties of intracules and Coulomb holes in
$He$, $Li^+$, $Be^{2+}$ and $Ne^{8+}$ and thus provide a transparent physical
picture for the interplay between the electron-nucleus attraction and
electron-electron repulsion in forming Coulomb holes around electrons in atoms
of different $Z$ values.
