First principles study of structural, electronic and optical properties of KCl crystal

The structural, electronic and optical properties of KCl crystal in B1, B2, B3 and T1 structures have been systematically studied using first-principle pseudopotential calculations. In addition, pressure-induced phase transition has also been investigated. It was found that when the pressure is below 2.8 GPa, the B1 structure is the most stable. Above 2.8 GPa KCl crystal will undergo a structural phase transition from the relatively open NaCl structure into the more dense CsCl atomic arrangement. Our results also suggested that at about 1.2 GPa structural phase transition from B3 to T1 will occur. When the pressure arrives at 39.9 GPa, the phase transition will occur from B2 to T1. In addition, we found KCl Crystal has indirect band gap in B2 structure and direct band gap in B1, B3 and T1 structures. The band gap value is the smallest in the T1 structure and is the largest in the B1 and B3 structures. Our calculations are found to be in good agreement with available experimental and theoretical results. The dielectric function and energy loss function of KCl crystal in four structures (B1, B2, B3 and T1) have been calculated as well as the anisotropy of the optical properties of KCl crystal in T1 structure.