The electronic structures of copper iodide crystal in γ phase and point defects associated with iodine and copper have been studied with relativistic density functional theory and embedded cluster method(DVM).Through the electronic densities of states of copper iodide crystal and its point defects

the emission and absorption mechanism are studied.The effects of all kinds of point defects on the emission spectrum of copper iodide crystal are also discussed.By the DVM method

(I

14

Cu

16

)

2+

cluster is used in the simulations of pure copper iodide crystal.In addition

on the basis of(I

14

Cu

16

)

2+

cluster

other clusters

such as copper vacancies

iodide vacancies

copper interstitial defects and iodide interstitial defects

have been studied as the main forms of its point defects.The excitation energy between different orbits is calculated by the transition state method

regarding the relaxation effect produced by the electronic transition in the crystal.Subsequently the computational result is compared with the experiments and the results by other simulation methods.The results of simulation of the pure copper iodide crystal show that the top of the valence band is consisted of I5p and Cu3d

and the bottom of the conduct band is consisted of Cu4s.The simulation result for the band gap of the pure crystal is 3.1eV

which is in good agreement with the experiment result.The calculation for point defects shows that the defects associated with the tetrahedron interstitial copper formed easier than that of other interstitial atoms in copper iodide crystal.The transition energies between Cu3d and Cu4s in copper tetrahedron interstitial defects are 3.2eV

which is presumed to be related to the broad luminescence bands of CuI crystal.The electronic structure of defects in CuI crystal is firstly calculated by DVM method.By the results

it can give some helpful clues for choosing certain dopants in copper iodide crystal to improve its scintillation charcteristic.And also it is very significative for the growth of super fast CuI sintillator.