The GW space-time method for the self-energy of large systems

We present a detailed account of the GW space-time method. The method incre ases the size of systems whose electronic structure can be studied with a c omputational implementation of Hedin's GW approximation. At the heart of th e method is a representation of the Green function G and the screened Coulo mb interaction W in the real-space and imaginary-time domain, which allows a more efficient computation of the self-energy approximation Sigma = iGW. For intermediate steps we freely change between representations in real and reciprocal space on the one hand, and imaginary time and imaginary energy on the other, using fast Fourier transforms. The power of the method is dem onstrated using the example of Si with artificially increased unit cell siz es. (C) 1999 Elsevier Science B.V.