This paper discusses whether it is advisable to use exchange and overlap corrections in calculations of the relation between the relative changes in the electron-capture probabilities DELTA-lambda/lambda and in the electron density at the nucleus DELTA-rho/rho. It is clearly shown that such corrections are not needed for DELTA-lambda/lambda measurements obtained from total electron capture decay rates.
Coussement, R., & Ladrière, J. (1990). Comments On the Use of Exchange and Overlap Corrections To Electron-capture Probabilities. Hyperfine Interactions, 62(3), 247-252. https://doi.org/10.1007/BF02397705 (Original work published 1990)