High-pressure structural phase transitions, electronic properties and intermediate states of the CaSe

In this study, ab initio calculations have been carried out in order to understand the effect of extreme external pressure on the crystal structure of CaSe. The crystal structure of the CaSe, one of the calcium chalcogen, is studied using the density functional theory (DFT) with the generalized gradient approximation (GGA) up to 250 GPa under high hydrostatic pressure. Structurally CaSe crystallizes in cubic NaCl-type (B1) structure (space group:Fm-3m) at ambient conditions. The results indicated that CaSe undergoes a structural phase transition from this cubic structure to another cubic CsCl-type (B2) structure (space group:Pm-3m) at high pressure. This transformation is based on two intermediate states with space group R-3m and C2/m. Additionally, the electronic band structures and density of states for the obtained B1 and B2 structures of CaSe have been calculated. According to these calculations, obtained band gap values are in a good agreement with the values reported in the literature.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author