Electronic Structures and Equation of State for Aluminium under High Pressure

The study for Al up to the pressure p=10 TPa, the compression 0/=10, by using the first principle calculations is performed. The energy band structures and electronic occupation numbers of the states for a series of lattice constants are presented. It follows from the energy band structures that s band always lies below the Fermi level. As the pressure increases, the bandwidths of s, p and d increase, and then the degree of hybridization become higher. So the electronic occupation numbers of s, d orbital change continuously. The effect of above mentioned changes to pressure is continuous too. In other words, sd transition is not the reason for a break in the slope of the shock Hugoniot for Al near 0.5 TPa, as claimed by Altshuler. The equation of state at T=0 K shows that bcc structure is softer than fcc. The results calculated by LMTO are different from the semi-empirical ones given by us previously. A new correct fitting for EOS from the results of LMTO is presented.