Bibliographic Details
| Title: |
Towards Exascale Ab Initio Materials Modelling |
| Authors: |
Smith, Matt, Durham, Ben, Jones, Philip, Tamerus, Arjen, Hasnip, Phil |
| Publisher Information: |
Zenodo, 2025. |
| Publication Year: |
2025 |
| Subject Terms: |
ARCHER2, CASTEP, HPC, Celebration of Science, MPI, algorithmic optimisation, Parallel, Density Functional Theory |
| Description: |
Plane-wave density functional theory (DFT) codes, i.e. those using a Fourier basis, consistently account for around a third of the total software usage on ARCHER2. Such codes typically decompose their 3D Fourier domain by distributing pencils of Fourier wave-vectors over MPI processes; 3D Fourier transforms are subsequently usually performed as sets of FFTs of lower dimensionality. The consequent inter-process communications are inherently quadratically-scaling and commonly determine the strong scaling limit of large materials modeling simulations. We present our development of a domain decomposition, implemented in CASTEP (www.castep.org), which, to our knowledge, constitutes a novel approach to communications in the DFT community. We describe our decomposition and load-balancing as a coupled two-dimensional optimisation problem. We explain how a logical 2D process grid effectively achieves linear-scaling communications, and how the consequent constraints on load-balancing are ameliorated by adopting and adapting several task-scheduling algorithms. We illustrate how the development performs in real-world simulations, dramatically reducing communication costs and significantly increasing the strong scaling limit. We illustrate efficient scaling on ARCHER2 to 4x as many processes as previously possible. |
| Document Type: |
Conference object |
| Language: |
English |
| DOI: |
10.5281/zenodo.15632030 |
| DOI: |
10.5281/zenodo.15632029 |
| Rights: |
CC BY NC ND |
| Accession Number: |
edsair.doi.dedup.....52993ef44d6378de9d1ba8a89c49f9b3 |
| Database: |
OpenAIRE |