Applied Physics Seminar | Towards Large-scale Quantum Accuracy Materials Simulations

Abstract:

Electronic structure calculations, especially those using density functional theory (DFT), have been very useful in understanding and predicting a wide range of materials properties. Despite the wide adoption of DFT, and the tremendous progress in theory and numerical methods over the decades, the following challenges remain. Firstly, many
widely used implementations of DFT suffer from domain-size and geometry restrictions,limiting the complexity of materials systems that can be treated using DFT calculations.
Secondly, there are many materials systems (such as strongly-correlated systems) where the widely used model exchange-correlation functionals in DFT, which account for the
many-body quantum mechanical interactions between electrons, are not sufficiently accurate.

This talk will discuss the recent advances towards addressing the aforementioned challenges, which provides a path for large-scale quantum accuracy materials simulations. In particular, the development of computational methods and numerical algorithms for conducting fast and accurate large-scale DFT calculations using adaptive finite-element discretization will be presented, which form the basis for the recently released DFT-FE open-source code. The computational efficiency, scalability and performance of DFT-FE will be presented, which can compute the electronic structure of systems containing many thousands of atoms in wall-times of few minutes. Some recent studies on the energetics of quasicrystals (ScZn 7.33 ) and dislocations in Mg using DFT-FE will be presented, which highlight the complex systems that can be tackled using DFT-FE. In addressing the second challenge, our recent progress in bridging highly accurate quantum many-body methods with DFT will be discussed, which is achieved by computing and using exact exchange-correlation potentials to improve the exchange-
correlation functional description in DFT.