"If you draw electrons away from the copper oxide layers, they become superconducting," Maier said. "Then the question is, what happens if you replace lanthanum with strontium, for instance. You do have different potentials, but you should also have different Coulomb repulsions on each site."
To achieve the sustained speed demonstrated in the simulation, the team made two fundamental changes to the DCA++ application, allowing it to delay memory-intensive operations and use a less memory-intensive data form. Both of these techniques exploit the fact that DCA++ uses the Monte Carlo approach, which relies on random sampling of a variable to explore systems such as the two-dimensional Hubbard model that do not lend themselves to an exact solution.
Between the two approaches, the team was able to boost the speed of the application by a factor of about 10, according to team member Marcus Eisenbach of ORNL's National Center for Computational Sciences. This increase in speed allows the team to look at a wider variety of materials in increased detail.
|Contact: Leo Williams|
DOE/Oak Ridge National Laboratory