Abstract
The electrical resistivity of disordered, partially ordered and long-range–ordered gold-copper alloys was calculated from first principles by applying the coherent-potential approximation (CPA) and the Kubo-Greenwood equation to lattices with 2 or 4 atoms per unit cell and varying the occupation probabilities within each cell. In a first step the composition-dependent resistivity for disordered alloys and alloys with the highest possible degree of order was calculated for the entire composition range. After this the experimental resistivity as a function of composition was modelled by calculating the resistivity based on reasonable values for the concentration-dependent order parameter and using lattice structures determined from the phase diagram for each concentration. The experimental resistivity for annealed alloys with its pronounced minima for the two stoichiometric compositions could be perfectly reproduced.