DFT calculations of structural, electronic, optical and elastic properties of scintillator materials BaCl2 and BaBr2

Detailed structural, electronic, optical and elastic properties with their pressure dependence of two barium halide scintillators are presented using first-principles calculations based on the density functional theory formalism. Only PBE-GGA results tally the closest with experimental results of a band gap of 4.26 eV for BaBr2 and 4.96 eV for BaCl2. The electron (m(e)*/m(0)) and hole (m(h)*/m(0)) effective masses are determined to be 0.88 and 0.95 for BaCl2 and 0.86 and 0.91 for BaBr2. The pressure dependence yields the pressure coefficient of the band gap as -4.34 x 10(-2) eV GPa(-1) and -3.77 x 10(-2) eV GPa(-1) for BaBr2 and BaCl2, respectively. All the elastic constants and the related parameters are calculated for both the halides. The optical and elastic properties clearly indicate the anisotropy along the three crystallographic directions of these two scintillators. The scintillation properties of the two compounds with and without doping are discussed in the light of these properties.