报告摘要：

　　Complex materials with novel properties, such as heavy-Fermion compounds and high-Tc superconductors, have drawn intensive interest not only for their potential applications in material and quantum information science but also for their scientific significance. However, accurately modeling these materials has been a challenge. Therefore, the development of advanced computational methods plays a critical role in materials science, chemistry, and condensed matter physics by providing valuable insights into the underlying physics and properties of novel materials. In the first part of this discussion, I will show the importance of the strongly-constrained and appropriately-normed (SCAN) functional with symmetry breaking in advancing the theoretical treatment of highly correlated materials. Specifically, I will share our insights on the puzzles of the heavy-fermion compound SmB6, including its highly debated quantum oscillations. Additionally, I will present our in-depth understanding of the electronic correlations in the newly discovered superconductor LaNiO₂. The charge density wave vectors predicted by our calculations are in good agreement with experimental observations, indicating the importance of electron-phonon coupling in this material.

　　In the second part, I will show how allowing for non-integer nuclear charges expands the space of computationally tractable electron systems that host competing electronic states. The simple 2-electron H2 molecule exemplifies this by showing the competition between charge transfer and strong correlations. Additionally, the emergence of competing electronic states in doped quasi-1D cuprate chains were demonstrated using this approach. Our findings are showing how non-integer nuclear charges can open a window for first-principles calculations of difficult many-electron phenomena.

报告人简介：

　　Dr. Ruiqi Zhang completed his Ph.D. in 2018 under the guidance of Prof. Jinlong Yang at the University of Science and Technology of China. He stated his postdoc appointment from 2018 at Tulane University and was promoted to be a research assistant professor in 2023. His recent focus involves investigating the electronic structures of strongly correlated materials like cuprates and nickelates, utilizing advanced density functional theory (DFT) with symmetry-breaking and Hamiltonian model calculations. His significant contributions in this field have led to an invitation to deliver an invited talk at the 2024 APS March Meeting.