Calibration of the isomer shift of the 14.4 keV transition of 57Fe

With the aim of calibrating Mössbauer spectroscopic measurements, the electron contact density was calculated on the Fe nuclear position in various iron compounds. The full-potential augmented-plane waves plus local orbitals (APW+lo) method within the local-density approximation was used, considering different approximations for the exchange and correlation potential. By comparison with experimental 57Fe Mössbauer data, the calibration constant α relating measured isomer shifts to the electron contact density was derived. An isomer shift calibration constant α = − 0.251 a.u.3 mm s − 1 has been obtained.