In this improved version, we have included several enhancements, namely the addition of electron density contributions with no spherical symmetry obtained from directional derivatives with respect to the distance vector between pairs of atoms, and by allowing the net atomic contributions to the electron density to change depending on what surrounds the molecules. Like the electron-electron and electron-nuclei exchange and correlation contributions, these non-spherical contributions can be solved analytically. Importantly, by constraining the fitted exchange and correlation coefficients to exact expressions, rather than viewing them as free parameters, we have successfully eliminated, in our numerical experiments, unphysical oscillations in the predicted interaction energies. This improvement is observed in both our full electron and ECP cases, particularly when extrapolating to extremely small interatomic distances.