Stability, elastic anisotropy, and electronic properties of Ca₂C₃

The systematic investigations of the mechanical, elastic, and electronic properties, and stability of the newly synthesized monoclinic C2/m-Ca₂C₃ are performed, based on the first-principles calculations. Ca₂C₃ is found to be mechanically and dynamically stable only from 0 GPa to 24 GPa. The elastic anisotropy studies show that Ca₂C₃ exhibits the elastic anisotropy increasing with the augment of pressure. Furthermore, using the HSE06 hybrid functional, the electronic properties of Ca₂C₃ under pressure are calculated. The structure can be regarded as a quasi-direct band gap semiconductor, and the pressure-induced direct-indirect band gap transition is studied in detail.