Treatment of Thermal Effects by Means of the Alloy Analogy Model
A scheme is presented that allows to account for finite temperature effects when calculating response functions or spectroscopic properties of solids. The approach is based on the alloy analogy model and treats thermally induced disorder as chemical disorder in substitutional alloys by means of the Coherent Potential Approximation (CPA). The reliability of the approach is demonstrated by calculations of the temperature dependent resistivity of ferromagnetic Fe. Calculations of angle-resolved photoemission show for increasing temperature the expected smearing of band-like features in the spectra, i.e. a transition from the so-called UPS to the XPS regime.