The influence of thermal vibrations on the average structure of cubic NaMgF3 perovskite:: a combined molecular dynamics and neutron diffraction study

The structure of NaMgF(3) has bean investigated by high-temperature neutron diffraction and molecular dynamics simulation. It was found that the apparent Mg-F bond contraction reported in previous work arises from large anisotropy in the distribution of F(-) ions. The cell parameter in the cubic phase is approximately 2% less than twice the average Mg-F bond distance, The consequences for computer simulation of perovskites of this dynamically induced reduction in cell volume are briefly discussed.