Mechanical stability and deformation potential in beryllium chalcogenides

The pressure dependence of the elastic constants associated with the fundamental band gap of beryllium chalcogenides has been studied by the state-of-the-art of Density Functional Theory. The resulting values of Cij were found to be strongly dependent on pressure. The fundamental band gap transition which occurs between Γ and X directions was found to shift linearly towards lower energy with increasing pressure, and yields a linear pressure coefficient of −22.7 (−25.85,−35.4) meV/GPa for BeS (BeSe, BeTe). The study is completed by the calculation of the effective hydrostatic deformation potential, which corresponds to 2.22 eV, 2.20 eV and 2.41 eV for BeS, BeSe and BeTe respectively.