Geometry and charge distribution of H centres in the fluorite structure

The analysis of experimental optical and spin-resonance data for the H centre gives a consistent picture of the local geometry and one-electron wavefunctions. One of the two ions in the F 2 - molecular ion remains very close to the perfect lattice site the other is at a distance close to that found in other F 2 - centres. This analysis is confirmed by atomistic calculations using the HADES code. The results are used to give a preliminary analysis of the self-trapped exciton data.