Isoelectronic Molecules. II. First- and Second-Order Physical Properties

It has been shown that first- and second-order physical properties of isoelectronic molecules are interrelated in a simple way. This follows from the fact that the corresponding first- and second-order operators are homogeneous functions of position and nuclear charge. The results are rigorously true for noninteracting electrons and can be extended to include interelectronic effects as well.