Professor Lucas Wagner (UIUC)

The collective behavior of electrons in materials gives rise to a multitude of behaviors at the macroscale, from semiconductors to superconductors to life. What's astonishing about this fact is that all these things in our everyday life are made up of nuclei and electrons, and the different combinations of nuclei and electrons result in the collective behavior we see at the microscale. The fundamental physics of nuclei and electrons is well-known, which in principle would allow us to predict the behavior of any material. However, the Schroedinger equation for many electrons is very challenging to solve. A particularly challenging aspect is that despite what we assume in introductory courses, electrons interact with each other strongly, resulting in strong electron correlation.

After many years of effort and progress, efficient and accurate solution methods for many-particle quantum systems have been developed, which allow near-exact solutions up to around 30 electrons and very accurate treatments of correlation up to around 1000 electrons. We find that accurate treatment of the microscopic behavior of electrons are essential to understanding the larger length scales macroscopic behavior we see. I will also discuss our recent efforts to create systematically improvable large-length scale understanding starting from these detailed first principles calculations.