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In the field of solid-state physics, the behavior of strongly correlated systems is a topic of much interest from both a theoretical and experimental point of view. Indeed, these materials have some specific electronic properties: the electrons located on the outer layer are so strongly linked with their atom that, in order to moving, a considerable energy is needed while, in usual materials, they can move almost freely. At low temperature, these strongly correlated systems can behave as insulators, with remarkable magnetic properties, or even as superconductors, meaning transferring electricity without any loss of energy.

High performance computing is paramount

Theoretical models developed for predicting these properties are well known. The equations that apply to the behavior of electrons are simple but solving them analytically is tricky if not impossible because it has to be done without any approximation. Hence the need of using numerical simulation: it is the core work of Sylvain Capponi, teacher-researcher at the Laboratoire de physique théorique (LPT) of the Institut de recherche sur les systèmes atomiques et moléculaires complexes (IRSAMC) in Toulouse. "High performance computing is paramount for describing these systems because the equations integrate a very high number of atoms, thus a very high number of variables", he said.

All GENCI’s resources mobilized

Thanks to a total of 30 million core hours awarded on all GENCI’s resources in 2015, his research group draws on the algorithms it developed for simulating different “exotic” proprieties of these materials, in particular magnetic and superconducting ones, at very low temperature. The results of their studies have been published in several articles in the reference reviews of the field. 

Physique théorique

Particles (in red) being put in order of charge on a honeycomb grid.
© S. Capponi and A. Läuchli - Phys. Rev. B 92, 085146 (2015)