Electronic Structure Effects in the Drude and Interband Absorption of Aluminum

Using Ashcroft's potential, the interband and Drude absorption in aluminum have been calculated. Two large peaks occur in the interband part of ${\epsilon }_2\left(\omega \right)$ at 0.5 and 1.6 eV. In addition, the interband absorption continues as $h\omega \to 0$. The optical effective mass is calculated with the result that $m_a^{*}=1.45\mathrm{}{m}_0$. Comparison with experiment is excellent. It is concluded that the optical spectrum of aluminum is completely understood in terms of the band structure. It is also pointed out that the optical peaks can be used to help determine the Fermi surface.