On the delta function broadening in the Kubo–Greenwood equation

Understanding DC electrical conductivity is crucial for the study of materials. Macroscopic can be calculated from first principles using Kubo–Greenwood equation. The procedure involves finding thermodynamic limit current response to an electric field that slowly switched on, and then taking switching rate zero. We introduce a nonlinear extrapolation executed in systems with periodic boundary conditions, which predicts close even very small systems. scheme also overcomes large part usual ambiguities definition finite numerically compare our method Landauer equation-based approach find both techniques consistent each other.