This work was partially supported by the National Aeronautics and Space Administration under Grant No. NAG1577.
Physical Review A
Nuclear physics, Sum rules (Physics)
It is shown that the semirelativistic approach, when applied consistently to atomic calculations involving the Thomas-Reiche-Kuhn sum rule or its applications, may lead to very inaccurate results.
Rustgi, M. L., Leung, P. T., & Long, S. T. (1988). Limitation of the semirelativistic approach in sum rules and related calculations in atomic physics. Physical Review A (General Physics), 37(5), 1775-1778.