ABSTRACT
In the literature, there are many instances of calculations being done at an equivalent level of accuracy for many ions of an isoelectronic sequence. It is then possible to establish patterns emerging along the sequence. But in some cases, marked deviations from smooth patterns occur, perhaps for a few neighboring ions, or even for a single ion in the sequence. It is important to know what the “normal” pattern should be, so that these deviations can be identified and explained, often in terms of configuration interaction or some other cancellation effect. Alternatively, and particularly, when calculations are done for just a single ion or a few neighboring ions, an isoelectronic pattern might be used to check the accuracy of such isolated results.
