A full implementation of the response iteration scheme for density functional calculations

We describe the implementation of the response algorithm for solving the Kohn-Sham equations and equations of similar structure that appear frequently in calculations of the structure of inhomogeneous many-body systems. The algorithm solves directly for the (spin) density. We have implemented the method for arbitrary geometries in a way that does not need the explicit calculation of unoccupied states. We apply the method to the two sample molecules C ₆H₆ and C₆₀, as well as to the metal clusters Mg₃₀ and Na₄₀. Starting from very rough guesses for the initial electron density, convergence is reached significantly faster than with previous update algorithms.