Calculations of hyperfine parameters in tin compounds

With the aim of calibrating Moessbauer spectroscopic measurements, the electric-field gradient and electron contact density is calculated on the Sn nuclear position in a number of Sn compounds representing all kinds of chemical bonding in solids. The full-potential linear-muffin-tin-orbitals method with the local-density approximation for exchange and correlation effects is used. By comparison with experimental 119Sn Moessbauer data the calibration constants relating measured isomer shifts and quadrupole splittings to the electron contact density and the electric-field gradient, respectively, are derived. The difference between the mean square radius of the 119Sn Moessbauer nucleus in its excited isomeric and ground states is found to be Δ left-angle r2 right-angle=(0.0072±0.0002) fm2, while the quadrupole moment of the excited 119Sn(24 keV,3/2+) nuclear state is obtained as |Q|=(12.8±0.7) fm2. The larger database considered and the use of a more accurate band-structure calculational scheme than in earlier works makes these numbers more accurate and provides improved calibration for Moessbauer spectroscopy. copyright 1997 The American Physical Society