Theoretical studies of structure, mechanics and electronic structures of four structures for CaSi2 under high pressure

Abstract

In this work, detailed DFT calculations of the structural, mechanical and electronic properties of crystalline CaSi2 with four different structures in the pressure range of 0–50 GPa are performed by GGA-PBE. It is found that the Enthalpy differences imply that the R[Formula: see text]m phase [Formula: see text] I41/amd phase [Formula: see text] P6/mmm phase transition in CaSi2 occur at [Formula: see text][Formula: see text]GPa, [Formula: see text][Formula: see text]GPa by using the XC of GGA, which is consistent with previous experiments and theoretical conclusions. Besides, the elastic stability criterion is used to study the change of the elastic constant of CaSi2 under pressures. In particular, the bulk modulus [Formula: see text], shear modulus [Formula: see text], Young’s modulus [Formula: see text], sound velocity [Formula: see text] and brittleness and toughness properties of CaSi2 under pressures are comprehensively studied for the first time. Finally, the changes of the anisotropy factor of CaSi2 are studied under different pressures, and the electronic structure is studied in detail.