Application of complex energy integration to selfconsistent electronic structure calculations

In electronic structure calculations the charge density is obtained by an energy integral over the one-electron Green's function, which especially for transition or rare earth metals is strongly structured. We show that a replacement of this integral by a contour integral in the complex energy plane allows a very efficient and accurate calculation of the charge density. Schrödinger's equation has to be solved only for a rather small number of complex energies along the integration path. We demonstrate the efficiency of this method for impurity calculations in Cu using the KKR-Green's function method and also discuss a possible application to band structure calculations.