Abstract:
The vibrational and electronic properties of several basic radiation defects in potassium
bromide are computed at the quantum mechanical level using a periodic supercell approach based
on hybrid functionals, an all-electron Gaussian-type basis set, and the CRYSTALcomputer code. The
exciton energy in alkali halides is sufficient to create lattice defects, such as F–H Frenkel defect pairs,
resulting in a relatively high concentration of single defects and their complexes. Here, we consider
eight defects: the electronic F
+- and F-centers (bromine vacancy without and with trapped electrons)
and their dimers; hole H-center (neutral bromine atom forming the dumbbell ion with a regular Br−
ion.); VK-center (Br−
2 molecular ion consisting of a hole and two regular ions); and two complex Br−
3
defects, combinations of several simple defects. The local geometry and the charge- and spin-density
distributions of all defects are analyzed. Every defect shows its characteristic features in Raman
spectra, and their comparison with available experimental data is discussed.
