Calculations of hyperfine parameters in tin compounds

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With the aim of calibrating M\"ossbauer 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 M\"ossbauer 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 M\"ossbauer nucleus in its excited isomeric and ground states is found to be {Δ}〈r²〉 =(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 M\"ossbauer spectroscopy.