Isoelectronic changes in X-alpha theory using a Z-transition state approach

Using a simple geometrical interpretation based on the Z-perturbation theory and the Hellman-Feynman theorem a Z-transition method is proposed for the calculation of total electronic energy difference of ions with respect to the isoelectronic neutral atoms. The method is particularly useful within the X-alpha like models wherein the negative ions are known to be inaccessible