The colour centers and self-trapped exciton in KMgF33
KMgF3晶体的色心和自陷态激子研究

The ab initio method is used to model the colour centers and self-trapped excitons in KMgF 3. The geometry optimization of the defect cluster, including the F center, shows that the relaxation of the lattice around the F center is very small. The calculated Mulliken populations for F center in its ground state and excite state show that the ground state wavefunction of F center is well localized, but the excited state wavefunction of it is more diffuse. Furthermore, our results show that the V K center moves toward the nearby interstitial site, but keeping the molecular axis along the 110] direction. The relaxation of the self-trapped excitons consists of an axial translation superimposed with a rotation. The calculated excitation energies of F center, V K center and the emission energy of self-trapped exciton are compared with their experimental values.