DETERMINATION OF THE NUCLEAR-QUADRUPOLE MOMENT OF FE-57

We determine the nuclear quadrupole moment Q of the most important Mossbauer nucleus Fe-57 by comparing experimental quadrupole splittings with calculated electric field gradients (EFG) for a large number of different Fe compounds. These ab initio calculations are based on the linearized-augmented place-wave band structure method. From the slope of the linear correlation between theoretical EFGs and experimental quadrupole splittings a new value of Q(Fe-57) = 0.16 b is deduced, twice as large as previously suggested. Our results should also stimulate nuclear physicists to revise nuclear structure shell model calculations of Q.