FIRST-PRINCIPLES STUDY OF THE OPTICAL-PROPERTIES AND THE DIELECTRIC RESPONSE OF AL

We investigate the optical properties and the dielectric response of Al through self-consistent Qb initio pseudopotential calculations. The frequency and wave-vector-dependent dielectric function of Al is calculated for both the real and imaginary parts within the random-phase approximation. The accuracy of the calculations is tested using Kramers-Kronig relations and sum rules. In the limit q --> 0, we find major optical peaks at 0.5 and 1.5 eV, which originated from the electronic structure, in good agreement with experimental data. For the wave vectors along the [100] direction, the electron-energy-loss function is calculated to examine the plasmon mode. Considering the exchange-correlation and core polarization effects, we find good agreement of the calculated plasma frequencies with experiments. The anisotropy of the plasmon dispersion is also investigated.