THE INFLUENCE OF THERMAL VIBRATIONS ON THE AVERAGE STRUCTURE OF CUBICNAMGF3 PEROVSKITE - A COMBINED MOLECULAR-DYNAMICS AND NEUTRON-DIFFRACTION STUDY

The structure of NaMgF3 has bean investigated by high-temperature neut ron diffraction and molecular dynamics simulation. It was found that t he apparent Mg-F bond contraction reported in previous work arises fro m 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 perovskit es of this dynamically induced reduction in cell volume are briefly di scussed.