Total energy and pressure in the Gaussian-orbitals technique. II. Pressure-induced crystallographic phase transition and equilibrium properties of aluminum

The phase stability of Al as a function of pressure and the bulk properties at equilibrium are explored via a series of all-electron, non-muffin-tin, local-density-functional calculations for the fcc and bcc structures. The techniques used are the linear combination of Gaussian-type orbitals (LCGTO) techniques which we have developed and used to test on bcc Li and fcc Ne recently. The zero-pressure static lattice cohesive energy and lattice constant are in good agreement with experiment, though the computed bulk modulus is less satisfactory. By comparison of the energies and enthalpies of the fcc and bcc structures at various compressions, the fcc phase is found to be more stable for pressures below 3.28±{}0.09 Mbar with the bcc structure more stable at higher pressure. The current results are compared to previous calculations in an attempt to resolve some major discrepancies between those more approximate calculations (which are both less costly and applicable to a wider variety of crystal structures than present implementations of LCGTO methodology).