Optical conductivity of disordered alloys calculated from first principles

The optical conductivity of random Ag-Au alloys was calculated applying the KKR-CPA method and the Kubo-Greenwood equation. Drude's law was fitted to the calculated conductivity for low frequencies to allow for a discussion of the free electron model and to obtain optical relaxation times which could be compared to experimental data. The imaginary part of the dielectric function calculated from the conductivity was split into intraband and interband contributions and was also compared to measured data. Possible reasons for the obtained differences in the interband transition onset energy as well as extensions of the formalism to more complicated systems are discussed.