Unified Access To Kohn-Sham DFT Solvers for Different Scales and HPC: The ELSI Project*

One major bottleneck in Kohn-Sham DFT is the solution of the Kohn-Sham eigenvalue equation to obtain the density matrix, which limits achievable system size. In this talk, we present updates to the ELectronic Structure Infrastructure (ELSI), an open-source effort that facilitates access to efficient Kohn-Sham solvers via a unified, code-independent interface for different system size scales, system types, and HPC architectures. Features that will be presented include support for several solver libraries (ELPA, libOMM, PEXSI, SIPs, CheSS) and a flexible, massively-parallel density-matrix-based restart method. Comparative benchmarks up to ten thousands of atoms on leading HPC resources will be shown. Special attention will be paid to the performance and scaling benchmark set created for this work, which is designed to be applicable to other aspects of electronic structure theory. These benchmarks will be the foundation of a decision layer to automatically select the optimal solver for a given problem based on the performance profile of the underlying HPC architecture.