Structural, Electronic and Elastic Properties of Potassium Iodide, under Pressure: An Ab-Initio Analysis Study

In this work, a recent version of the full potential linear muffin-tin orbitals (FP-LMTO) method was employed, using the local density approximation (LDA) within the framework of density functional theory (DFT). This approach was applied to study the structural, electronic and elastic behavior of the potassium iodide (KI) compound under pressure. The calculated structural parameters exhibit strong agreement with available theoretical and experimental data. The RS phase was identified as the most stable structure for KI material. The phase transition from NaCl-type (B1) to CsCl-type (B2) phase occurs at pressure of 1.633 GPa, which is quite consistent with the experimental values. Furthermore, the band structure of KI revealed a wide-band gap semiconductor behavior across all examined phases. The obtained bulk modulus values were relatively low, suggesting weak resistance to fracture. The elastic constants for KI in RS, CsCl, ZnS, HCP, and WZ structures were determined and found to meet Born’s stability conditions. We esteem, there is no values available in the literature on the elastic constants for KI in CsCl, ZnS and WZ phases. All analyzed structures displayed ductile characteristics and ionic bonding features. Additionally, anisotropic properties were observed in all phases. The compound’s stiffness was evaluated using Poisson’s ratio and Cauchy’s pressure. Results indicated that the CsCl phase is the most rigid among the studied configurations.