First-principles investigation of the thermo-physical properties of Ca3Si4

The first-principles calculations were applied to investigate the thermo-physical properties of Ca3Si4 compound with increasing pressure. Those properties are based on density functional theory (DFT) method within the generalized gradient approximation (GGA) and local density approximation (LDA) for exchange and correlation. The optimized lattice constant and formation enthalpy are in good agreement with the experimental data and other theoretical data available. The calculated band structures confirm that Ca3Si4 is a semiconductor with an indirect band gap of 0.363 eV (GGA) and 0.311 eV (LDA) at 0 GPa, and the calculated band gap decreased with the increasing pressure. The elastic constants, elastic anisotropy, elastic moduli and Poissonʹs ratio of Ca3Si4 have also been obtained under high pressures. The Debye temperature, heat capacity, coefficient of thermal expansion and Grüneisen parameter have also been calculated in the quasiharmonic Debye model.