Optimizing GW for Petascale HPC and Beyond*

The traditional GW-Bethe-Salpeter (BSE) approach has, in practice, been prohibitively expensive on systems with more than 50 atoms. We show that through a combination of methodological and algorithmic improvements, the standard GW-BSE approach can be applied to systems with hundreds of atoms. We will discuss the massively parallel GW-BSE implementation in the BerkeleyGW package (on-top of common DFT packages) including the importance of hybrid MPI-OpenMP parallelism, parallel IO and library performance. We will discuss optimization strategies for and performance on many-core architectures.