Temperature and pressure effects on the elasticity behavior, electronic and vibrational properties of Al, Li, LiAl and Li2Al: A density functional theory study

A detailed investigation of the structural, elastic, electronic and thermodynamic properties of fcc-Al, hcp-Al, hcp-Li, LiAl and Li2Al has been carried out by means of density functional theory calculations combined with ultra-soft pseudo-potentials. The calculated lattice parameters, elastic constants and elastic moduli are compared with the available results. The agreement between our calculated results and the experimental data is good. The density of states, band structures and electronic heat capacity coefficients are also obtained. At room temperature, the fcc → hcp phase transition of Al would occur at 207.27 GPa. Besides, the dependencies of bulk modulus, heat capacity, thermal expansion and Debye temperature on the temperature are systemically determined. Several interesting features in these quantities are observed at high temperature. It is worth noting that, the temperature effects, mainly represented by lattice vibrations and mobile electrons, are taken into account within the full-electronic quasi-harmonic approximation.