A first-principles study of bulk aluminum at high pressure

Using ab initio total energy calculations based on density functional theory and a procedure based on minimization of the Gibbs free energy, we calculate the Gibbs free energy for face-centered cubic and hexagonal close-packed aluminum in the temperature range from 0 to 900 K. It is shown that at zero temperature an fcc → hcp phase transition occurs at 181 GPa, and when the temperature is increased to 900 K the phase transition pressure increases slightly. As the pressure increases, the Gruneisen parameter first decreases significantly, then increase sharply at the phase transition pressure, and finally decrease again with further increasing volume compressibility. It turns out that the temperature and pressure have considerable effects on the Gruneisen parameter in certain ranges.