The nuclear quadrupole moment (NQM) of the I-pi = 3/2(-) excited nuclear st
ate of Fe-57 at 14.41 keV, important in Mossbauer spectroscopy, is determin
ed from the large-scale nuclear shell-model calculations or Fe-54, Fe-57, a
nd also from the electronic ab initio and density functional theory calcula
tions including solid state and electron correlation effects for the molecu
les Fe(CO)(5) and Fe(C5H5)(2). Both independent methods yield very similar
results. The recommended value is 0.15 (2) e b. The NQM of the isomeric 10 in Fe-54 has also been calculated. The new NQM values for Fe-54 and Fe-57
are consistent with the perturbed angular distribution data.