First principles study on the structures and properties of aluminum under high pressures

The structural, electronic, elastic and thermodynamic properties of aluminum were investigated using the first principles method based on density functional calculations in the region of 0GPa~100GPa. The unit cell volume and atomic positions were optimized with generalized gradient approximation (GGA), all calculated properties are in excellent agreement with the available experimental results, which imply the reliability of the present calculation method. The results show that aluminum is structural, mechanically and dynamically stable in the region of 0GPa~100GPa. With the increase of pressures, the cell parameter and cell volume of aluminum decrease, charge density between atoms increase. The bulk modulus, shear modulus, Young's modulus and Poisson ratio are estimated by Voigt-Reuss-Hill approach. The B/G values and Cauchy pressures indicate aluminum possesses ductility, the ductility properties of aluminum enhance with increasing pressures. The heat capacity of aluminum increases with temperature at constant pressure while decreasing with pressure at constant temperature.