Massively parallel cubic-scaling GW calculations with the OpenAtom software

OpenAtom is an open source, massively parallel ab initio density functional software package based on plane waves and pseudopotentials (http://charm.cs.uiuc.edu/OpenAtom) that takes advantage of the Charm++ parallel framework. We will describe a cubic-scaling massively parallel implementation of the GW approximation (L. Hedin, Phys. Rev. 139, 1965) to the electronic self-energy that is useful for beyond-DFT calculations of electronic band structures. After a brief summary of the OpenAtom and Charm++ frameworks along with the main ideas behind our cubic-scaling approach (Kim, Martyna, Ismail-Beigi, Phys. Rev. B 101, 2020), we will describe the approach we employ for its parallelization (along with benefits and tradeoffs involved) and some examples of its parallel performance on large supercomputers.