High performance computing of DGDFT for tens of thousands of atoms using millions of cores on Sunway TaihuLight.

High performance computing (HPC) is a powerful tool to accelerate the Kohn-Sham density functional theory (KS-DFT) calculations on modern heterogeneous supercomputers. Here, we describe a massively parallel implementation of discontinuous Galerkin density functional theory (DGDFT) method on the Sunway TaihuLight supercomputer. The DGDFT method uses the adaptive local basis (ALB) functions generated on-the-fly during the self-consistent field (SCF) iteration to solve the KS equations with high precision comparable to plane-wave basis set. In particular, the DGDFT method adopts a two-level parallelization strategy that deals with various types of data distribution, task scheduling, and data communication schemes, and combines with the master-slave multi-thread heterogeneous parallelism of SW26010 processor, resulting in large-scale HPC KS-DFT calculations on the Sunway TaihuLight supercomputer. We show that the DGDFT method can scale up to 8,519,680 processing cores (131,072 core groups) on the Sunway TaihuLight supercomputer for studying the electronic structures of two-dimensional (2D) metallic graphene systems that contain tens of thousands of carbon atoms.