Isomer shifts and hyperfine fields in iron compounds

The 57 Fe isomer shifts and magnetic hyperfine fields in several iron compounds are computed using self-consistent spin-polarised electronic structure calculations within the LMTO formalism. A good account of experimental trends is obtained, and a value for the mean square radius difference between the two nuclear states involved in the 57 Fe isomeric transition of Delta (r 2 )=-20*10 -3 fm 2 is derived. In the compounds considered the hyperfine field is found to scale with the local iron moment except for those cases where the Fe majority band is fully occupied.