A team led by Vikram Gavini, associate professor of mechanical engineering at the University of Michigan, used the supercomputer at the Oak Ridge Leadership Computing Facility (OLCF) to perform a simulation of a 10,000-atom magnesium dislocation system, a feat that could allow scientists to understand which alloying materials to add to improve magnesium’s ductility. By simulating a system tenfold larger than was possible with previous codes and 20 times faster, the team ultimately achieved a 200-fold speedup, running at 46 petaflops and earning an Association for Computing Machinery Gordon Bell Prize finalist nomination.
“Using Summit, we were able to perform the largest simulation to date of this dislocation system in magnesium that we believe is crucial to improving its ductility,” Gavini said. If scientists can simulate alloys with high accuracy, they will gain the ability to prescreen new materials before experimental testing, thus accelerating the introduction of new materials. And with knowledge of the energetic principles involved in certain types of dislocations, experimentalists can more easily develop recommendations for new alloys.
To understand materials, Gavini’s team performs density functional theory (DFT) calculations, which focus on the electronic structure of materials systems. Until now, existing DFT codes have been incapable of handling the large system sizes needed to accurately model these defects. To address these limitations, Gavini’s research group has, over the years, developed methods and algorithms for fast, accurate, and scalable DFT calculations.
Last year, team members attended an OLCF hackathon, a hands-on workshop during which researchers port their existing codes to GPUs with the help of expert mentors. Before the hackathon, they had no existing GPU code, but at the event they were able to move their code onto Summit, the world’s most powerful and smartest supercomputer for open science.
“All of our algorithms were stable on CPUs, but we knew we had to have a GPU-based code to fully take advantage of an architecture like Summit’s,” Gavini said of the system at the OLCF, a US Department of Energy (DOE) Office of Science User Facility located at DOE’s Oak Ridge National Laboratory.
The team spent 6 months porting 90 percent of its code, DFT-FE (DFT with Finite Elements), to GPUs after earning time on Summit through a Director’s Discretionary allocation. The researchers performed smaller simulations of magnesium dislocation systems with around 2,000 atoms on Summit before performing a final 10,000-atom simulation. At 13.6 nanometers by 13.6 nanometers by 1.2 nanometers, this final simulation provided the team with the accuracy needed to understand the energetic properties of the magnesium system at high fidelity.
Researchers hope the GPU-accelerated version of the code will serve as a computational tool for scientists to prescreen and identify crucial alloys that experimentalists could further refine.
Source: Oak Ridge National Laboratory — https://www.olcf.ornl.gov/2019/10/28/search-for-lightweight-alloying-solutions-earns-team-a-gordon-bell-finalist-nomination/